Acne Science

Acne Science

Acne is a complex disease. The Acne Science section covers a range of scientific topics related to the development of acne and the available treatments. For more discussions about common acne questions, refer to our Frequently Asked Acne Questions page.

What Causes Acne?

Inflammatory Acne Papules Skin and Cellular View
Inflammatory Acne Papules Skin and Cellular View

Acne is a complex disease and many factors can contribute to the development of acne symptoms. Every case of acne is unique and the blend of factors that cause acne varies between individuals. This section contains a list and discussion about the factors that are major contributors to the development of acne symptoms.

Acne at a Cellular Level

Whitehead Pimple Skin and Cellular View
Whitehead Pimple Skin and Cellular View

Most people can recognize acne when it presents on the face or body. Most people also have the vague understanding that acne is associated with oily skin and an excess production of sebum. But beyond that, few people really grasp what is actually happening at the microscopic level of a pimple. This section discusses the formation of acne lesions at a microscopic level.

The Sebaceous Glands

Hair Follicle, Sebaceous Glands and Sebum (Wikipedia)
Hair Follicle and Sebaceous Glands (Wikipedia)

Sebaceous glands produce and secrete sebum, which is responsible for moisturizing and protecting skin and hair. Sebaceous glands are essential components of healthy skin. Damaged or malfunctioning sebaceous glands contribute to many dermatological conditions, including acne vulgaris. This section discusses the structure and function of the sebaceous glands.

Sebum

Composition of Human Sebum
Composition of Human Sebum

Sebum is a naturally occurring substance that moisturizes, lubricates and protects the skin and hair. Sebum is produced by the sebaceous glands of mammals. Healthy sebum production is essential for the integrity and normal function of the skin as a protective organ. Sebum is also an important source of energy (food) for acne-causing Propionibacterium acnes bacteria. This section discusses the biology of sebum and its role in the development of acne symptoms.

What is Propionibacterium acnes?

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

Propionibacterium acnes (P.acnes) is a bacteria that can colonize the the skin and hair follicles. Excessive growth of this bacteria in the skin contributes to acne vulgaris. Propionibacterium acnes (P. acnes) is a bacteria that grows deep inside of pores, where it feeds on the sebum that is produced by the sebaceous glands that surround the base of the hair shaft. Most individuals with acne symptoms have an overgrowth of P. acnes bacteria in their skin. Several research studies have indicated that specific strains of P. acnes bacteria are commonly associated with acne vulgaris. This section details what P. acnes bacteria are and how it contributes to acne symptoms.

The Antibiotic Susceptibility of Propionibacterium acnes

Bacteria Antibiotic Susceptibility Test Plate (credit - Wikipedia)
Bacteria Antibiotic Susceptibility Test Plate (Wikipedia)

Propionibacterium acnes is a bacteria that grows within hair follicles and contributes to acne symptoms. Antibiotics reduce the growth of acne-causing bacteria and are a common treatment for acne symptoms. For the past 50 years, physicians and researchers have been screening the susceptibility of Propionibacterium acnes (P. acnes) bacteria to different antibiotics. The results from these studies clearly demonstrate that in many places, P. acnes bacteria are becoming increasingly resistant to certain classes of antibiotics. This section discusses the results of research studies about the antibiotic sensitivity of P. acnes bacteria.

The Antibiotic Families

Tetracycline Antibiotic Capsules
Tetracycline Antibiotic Capsules

There are many different families of antibiotics. Each antibiotic family targets bacteria in a unique way. Each antibiotic family tends to be more effective against certain types of bacteria, and less effective against others. Antibiotics from several different families are used for the treatment of acne. Antibiotics can be used applied topically or ingested orally. The route of delivery, the ability of an antibiotic to accumulate in the skin and the susceptibility of P. acnes bacteria to an antibiotic all impact the efficacy of a given antibiotic treatment. This section discusses the different classes of antibiotics that are used in the treatment of acne.

How Do Bacteria Become Resistant to Antibiotics?

Bacteria Cell (Wikipedia)
Bacteria Cell (Wikipedia)

Bacteria can become resistant to antibiotics that they were susceptible to in the past. There are several factors which contribute to the growing problem of antibiotic-resistant bacteria. This section discusses the many ways that antibiotic resistance may occur, as well as the conditions and environments that promote the development of antibiotic-resistant bacteria.

The Antibacterial Activity of Essential Oil

Eucalyptus Essential Oil Vials
Eucalyptus Essential Oil Vials

Many essential oils and other plant extracts have antimicrobial properties which can be helpful for health and wellness applications. There is an incredible diversity of essential oils and other plant extracts available on the market today. This selection provides a plethora of options for both professional and casual practitioners of Naturopathic remedies for many health issues, including acne. This section discusses the scientific research into the antibacterial properties of plant essential oils.

Avoiding Negative Interactions Between Medications

Physicians Desk Reference (PDR)
Physicians Desk Reference (PDR)

A medication is contraindicated when there is an existing condition that makes its use inadvisable. Certain medications can be contraindicated in specific groups of people (eg. pregnant women) or in combination with other medications (eg. aspirin and warfarin). Basically, some medications are contraindicated with one another because taking them together is known to cause potentially serious problems. This section discusses how to learn more about medications and avoid negative drug interactions.

How Do Acne Scars Form?

Ice Pick Acne Scars on Cheek
Icepick Acne Scars on Cheek

Acne scars are the result of tissue damage caused by inflammatory acne. The vast majority of acne scars are caused by from persistent cases of inflammatory acne affecting the same area of skin. Individuals who suffer from frequent nodular and cystic acne outbreaks (Acne Types: 3-4) are at a very high risk of developing permanent acne scarring. This is particularly true when a region is affected by overlapping acne outbreaks, with no opportunity for the skin to completely heal between outbreaks. This section discusses the different factors that contribute to the development of acne scars.

Avoiding Negative Interactions Between Medications

Accutan Contraindication from PDR

What Does “Contraindicated” Mean?

Isotretinoin (Accutane) Pregnancy Contraindication Warning
Isotretinoin (Accutane) Pregnancy Contraindication Warning

A medication is contraindicated when there is an existing condition that makes its use inadvisable. Certain medications can be contraindicated in specific groups of people (eg. pregnant women) or in combination with other medications (eg. aspirin and warfarin). Basically, some medications are contraindicated with one another because taking them together is known to cause potentially serious problems. Before using any medication, it is important to verify (preferably through consultation with a licensed medical provider) that the medication is not contraindicated with any medical conditions you may have, or with any medications you may already be taking.

How Can I Check For Contraindications?

Educate Yourself About Your Medications

The more you learn about a particular topic, the more likely you are to make good decisions and avoid mistakes when dealing with that topic. This is especially true for medical conditions and medications. At the end of the day, it is your body and you are responsible for what you put in it (or on it). It is the patient’s responsibility to educate themselves as best as possible about any medications they are taking, or are considering taking.

An excellent way to start educating yourself about the medications that you are taking is by reading the patient inserts that come with a medication. This information outlines many of the important features, and risks, of a medication. For more detailed information, the physician’s insert for the medication is a good start. These can be found online by using google to search for the term “Physician Insert” plus the name of your medication. The Physicians’ Desk Reference is another excellent resource to learn more about medications and their contraindications.

The Physician’s Desk Reference (PDR)

Physicians Desk Reference (PDR)
Physicians Desk Reference (PDR)

The Physicians’ Desk Reference (PDR) is a an annually updated compilation of manufacturers’ prescribing information for prescription medications. It is designed to provide physicians with the all of the legally mandated information relevant to available prescription medications. While it is widely used by medical professionals, it is also a valuable resource for patients and consumers. The Physician’s Desk Reference is available in many libraries, bookstores and online from sources like Amazon.com.

Acne at a Cellular Level

Inflammatory Acne Papules Skin and Cellular View
Whitehead Pimple Skin and Cellular View
Whitehead Pimple Skin and Cellular View

Most people can recognize acne when it presents on the face or body. Most people also have the vague understanding that acne is associated with oily skin and an excess production of sebum. But beyond that, few people really grasp what is actually happening at the microscopic level of a pimple.

Understanding the physiological and pathological processes behind acne can help you sort out what treatments and advice can help you make positive changes in your acne. A better understanding of the science of acne can also help you identify the claims that have no basis in scientific reality and should be ignored.

What Causes Acne?

Healthy and Infected Follicle
Healthy and Infected Follicle

At a very basic level, acne results from a combination of factors that result in blocked pores, an accumulation of sebum, bacterial growth and inflammation. Acne generally occurs within the hair follicle, when excess sebum is produced by the sebaceous glands and creates a plug that blocks the follicle.

Clogged follicles create a micro-environment that favors the growth of certain types of bacteria, such as Propionibacterium acnes and Staphylococcus aureus. The presence of this bacteria triggers an immune response, which is characterized by inflammation, increased blood flow (redness) and the recruitment of white blood cells to the follicle.

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

The initial inflammation of an acne lesion can often cause additional damage to the follicle and surrounding tissue, increase the growth of bacteria and induce further swelling and discomfort. In some individuals, this process becomes a vicious cycle and leads to extensive acne and significant damage to the skin and the subcutaneous matrix that supports healthy skin. Severe and repeated damage that is caused by inflammatory acne lesions can cause permanent acne scars.

Sebum and a Healthy Follicle

Composition of Human Sebum
Composition of Human Sebum

Sebum is a mixture of fatty acids and lipids that is essential for lubricating and protecting healthy skin. Sebum is produced by Sebaceous Glands, which are attached to the base of hair follicles. In a healthy follicle, the sebaceous gland produces the appropriate amount of sebum to maintain the health of the surrounding skin, and that sebum is efficiently extruded along with the hair.

For individuals with acne, several things can happen that disrupt the delicate balance of sebum production. Normal sebaceous glands are relatively small and produce a minimal amount of sebum. However, excessive growth of the sebaceous glands (sebaceous hyperplasia) and overproduction of sebum can be an important contributor to acne symptoms. Sebaceous hyperplasia can be triggered by increases in androgen hormones, which is common for males during puberty.

Sebaceous Glands and Sebum Production (Toth)
Sebaceous Glands and Sebum Production (Toth)

Sebum itself is created by the breakdown of the cells that form the sebaceous gland. Sebaceous cells replicate at the base of the gland and move up towards the hair follicle as the new cells proliferate. As the maturing cells approach the hair follicle, they undergo apoptosis and die. The cells are lipid rich (oil) and the byproducts left over as the cells dissolve composes the sebum that lubricates and protects the hair. Proliferation of the sebaceous glands causes an increase in the production of sebum, which is often manifested as oily skin and hair.

UV Fluorescence of Propionibacterium acnes Bacteria in Nose Pores
UV Fluorescence of Propionibacterium acnes Bacteria in Nose Pores

Sebum can also serve as a nutrition source for bacteria that reside inside the hair follicle, such as P. acnes and S. aureus. Excess amounts of sebum can encourage bacterial growth and lead to inflammation, redness and an infiltration of white blood cells (pus). If a hair follicle is plugged near the surface, this process can often lead to the formulation of a surface pustule (whitehead). However, for many people who suffer with inflammatory acne, the pustules are often formed deep in the tissue and away from the surface. These deep-seated pustules are responsible for nodular and cystic acne symptoms (Acne Types: 3-4).

Type 4 Acne on Face
Type 4 Acne is Likely to Cause Acne Scars

The deep-seated pustules that form in nodular and cystic acne lesions are surrounded by tissue and it is difficult to drain the pus and bacteria to the surface (eg. “pop” or lance the pimple). Individuals with acne lesions that are significantly inflamed or painful should generally avoid trying to “pop” these pimples at home. Effectively and safely draining these lesions can reduce symptoms and accelerate healing, but these procedures should be performed by a trained medical professional. Many times, continued sebum production, bacterial growth and inflammation within a plugged follicle can cause the follicle to rupture and drain into the surrounding tissue. This process can lead to further inflammation, dissemination of the bacterial infection, worsening acne symptoms and the formation of acne scars.

The Antibacterial Activity of Essential Oil

Eucalyptus Essential Oil Vials

Many essential oils and other plant extracts have antimicrobial properties which can be helpful for health and wellness applications. There is an incredible diversity of essential oils and other plant extracts available on the market today. This selection provides a plethora of options for both professional and casual practitioners of Naturopathic remedies for many health issues, including acne.

Antimicrobial Properties of Essential Oil

Clove Flowers
Clove Flowers

Much of what makes up an essential oil are molecules which are part of a plant’s natural defense system. These molecules have been designed by millions of years of evolution to protect the plant against potential enemies. These enemies can be bacteria, fungi, viruses, other plants, insects and other animal predators.

Some components of essential oil have antibacterial, anti-viral and anti-fungal activity. Other components in the essential oil are designed to prevent predation by insects and other animals. Some essential oils may even be toxic to other plants and are designed to help inhibit the growth of competing plants.

In the last twenty years, a great deal of scientific research has been done to characterize the antimicrobial activity of many essential oils. Using this knowledge can help guide better decisions when designing effective Naturopathic treatments for acne.

The Antibacterial Activity of an Essential Oil Depends on the Species of Bacteria

Some essential oils are highly toxic to certain species of bacteria, but are harmless to others. While some essential oils are effective against a broad spectrum of different bacteria, others are only useful against very specific types of bacteria.

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

When designing a Naturopathic acne treatment that includes essential oils, it is important to be aware of these differences. To better improve the design of acne treatments, we have compiled scientific reports from many sources in order to help identify which essential oils are likely to be most effective against acne-causing bacteria, such as Propionibacterium acnes (P. acnes) and Staphylococcus aureus (S. aureus).

Many essential oils also have anti-inflammatory properties which may  also help in the treatment of acne symptoms.

What Essential Oils are Effective Against Propionibacterium acnes Bacteria?

Tea Tree Flowers
Tea Tree Flowers

Scientific research reports indicate that there are many types of essential oil that are active against P. acnes bacteria. Tea Tree essential oil is one of the most popular essential oils for skin care applications, and the research shows that it is indeed toxic to P. acnes bacteria (although not as much as some other essential oils). Thyme, Clove and Cinnamon essential oil have broad spectrum antibacterial properties, and are also effective against P. acnes as well.

Unfortunately, many of the essential oils with significant antibacterial activity against P. acnes bacteria can also be fairly irritating to the skin, particularly at higher concentrations. However, there are several essential oils which have excellent antibacterial properties and a lower risk of skin irritation. For example, several different kinds of Citrus essential oils, were highly toxic to P. acnes bacteria but tend to be fairly mild to the skin. Lemongrass essential oil is another a potentially useful option for acne treatments.

Antibacterial Activity of Essential Oil Against Other Bacterial and Fungal Infections

There have been many research studies which examine the ability of different essential oils to inhibit or kill different kinds of infectious bacteria and fungi. No matter what kind of application you have in mind – whether it is designing a Naturopathic acne treatment or developing a natural disinfectant – understanding the antimicrobial properties of different essential oils is a critical first step. To help improve the understanding of these properties, we are working on developing a comprehensive database that about essential oils and their antimicrobial activities.

Selected Results from Research Studies on the Antibacterial Activity of Essential Oils

Minimum Inhibitory Concentrations of Many Essential Oils Against 5 Strains of Propionibacterium acnes (Luangnarumitchai)
Minimum Inhibitory Concentrations of Many Essential Oils Against 5 Strains of Propionibacterium acnes (Luangnarumitchai)
Inhibition of Propionibacterium acnes Growth by 10 Essential Oils (Zu)
Inhibition of Propionibacterium acnes Growth by 10 Essential Oils (Zu)
Antimicrobial Activity of 21 Essential Oils Against Propionibacterium acnes and Other Bacteria (Prabuseenivasan)
Antimicrobial Activity of 21 Essential Oils Against Propionibacterium acnes and Other Bacteria (Prabuseenivasan)
Antibacterial Activity of Many Essential Oils Against 10 Species of Bacteria (Hammer)
Antibacterial Activity of Many Essential Oils Against 10 Species of Bacteria (Hammer)

References

Activities of Ten Essential Oils towards Propionibacterium acnes and PC-3, A-549 and MCF-7 Cancer Cells. Zu, et al. 2010.
Antimicrobial Activity of Essential Oils Against Five Strains of Propionibacterium acnes. Luangnarumitchai, et al. 2007.
Antimicrobial activity of essential oils and other plant extracts. Hammer, et al. 1999.
Antioxidant Activities and Volatile Constituents of Various Essential Oils. Wei, et al. 2007.

Anabolic Steroids and Acne

Muscles and Epigenetic Adaptation

What are Anabolic Steroids?

Arnold Used Lots of Anabolic Steroids
Arnold Used Lots of Anabolic Steroids

Anabolic Steroids (aka Roids, Juice, AAS, etc) are molecules that mimic the shape and function of androgen hormones (eg. Testosterone). Anabolic Steroids are generally used to stimulate protein synthesis and muscle growth.

Anabolic steroids should not be confused with corticosteroids, which are immune suppressants and can actually inhibit muscle growth. Corticosteroid injections are sometimes used to treat acute inflammation in severe acne lesions. Anabolic Steroids are never used as an acne treatment, and their use can cause or worsen acne symptoms.

There are numerous medical conditions for which Anabolic Steroids are legitimately used as treatments, but Anabolic Steroids are better known for their use as performance enhancing drugs. Virtually all major sporting leagues ban the use of Anabolic Steroids, although this doesn’t necessarily prevent their use by athletes. Anabolic Steroids use by individuals for aesthetic purposes is also common in some populations.

Risks and Side Effects of Anabolic Steroid Use

There is widespread concern and controversy about the danger posed by both aesthetic and performance enhancing use of Anabolic Steroids. While some of the danger may be overstated, there are many well-known side effects associated with the use of Anabolic Steroids, including: Growth disruption in adolescents, hormone balance problems, accelerated male pattern balding, cardiovascular problems, contaminated/counterfeit medications, psychological problems (e.g. roid rage) and acne vulgaris.

Androgens Drive Muscle Growth
Androgen Hormones Drive Muscle and Body Hais Growth

Research shows that negative side effects of Anabolic Steroid use tend to occur in a dose dependent fashion. Higher and more frequent dosing of Anabolic Steroids is generally associated more frequent and severe side effects. The side effect profile is also dependent on the precise type of Anabolic Steroid being used. With the rapid expansion in designer Anabolic Steroids over the last two decades, a tremendous diversity of options now exists in the marketplace.

How Anabolic Steroids Work

Testosterone is an Androgen Hormone
Testosterone is an Androgen Hormone

Androgens are the primary hormones responsible for many of the masculine characteristics that differentiate males and females. While females naturally produce androgen hormones like testosterone, they tend to produce much less than males. Anabolic Steroids are usually compounds that are structurally similar to the testosterone.

Focused scientific development of Anabolic Steroids was pioneered by the Soviet Union to improve their competitiveness in international athletic competitions (e.g. the Olympics. The first Anabolic Steroids were simple blends of testosterone and its naturally occurring derivatives. However, these first generation steroids not only increased muscle growth but also had potent masculinizing effects on the user. These effects were most evident in female athletes, with the women of the East German Olympic teams of the 1970’s and early 80’s being the most famous examples. Starting in the 1970’s doctors and scientists began researching new testosterone derivatives that would encourage muscle growth with fewer side effects, so called “designer steroids”.

Many of the cells that compose the human body have sensors called “androgen receptors” that mediate cellular responses to androgen hormones. When the androgen hormone is detected by the cell it stimulates changes in gene expression and metabolism in the cell. However, not all cells respond the same way when they are activated by an androgen hormone. Whereas muscle cells may be stimulated to grow and multiply, other cells, like those in the testes, may actually slow their growth.

Diagram of how Molecular Modifications Affect Anabolic vs Androgenic Profile
Diagram of how Molecular Modifications Affect Anabolic vs Androgenic Profile

Androgen receptors are not exactly the same from cell to cell. There are slight differences between the androgen receptors (and their downstream signalling pathways) depending on the type of cell.  The androgen receptors on certain have a high affinity for some androgen hormone derivatives, but a low affinity for others. Over the last thirty years, scientists have been working to develop “designer steroids” that preferentially stimulate the androgen receptors on muscle cells. Significant progress has been made in this pursuit, and today’s designer steroids have far fewer androgenic side effects than those used by the Soviet Union thirty years ago. That said, virtually all Anabolic Steroids still have some level of negative side effects.

Anabolic Steroids and Acne

One of the most common side effects of Anabolic Steroid use is the development of acne on the face, chest and back. The development of acne symptoms is generally caused by the increased activity of the sebaceous glands in response to elevated levels of androgen hormones. High concentrations of androgens (eg. Testosterone) in the body can increase the size and growth rate of the sebaceous glands.

Effect of DHT Androgen on Sebaceous Gland Activity (Akamatsu)
Effect of DHT Androgen on Sebaceous Gland Activity (Akamatsu)

The increase in sebaceous gland activity generally leads to a corresponding increase in sebum production. High levels of sebum production can increase the incidence of clogged pores and induce the growth of acne-causing bacteria, such as Propionibacterium acnes. P. acnes bacteria use sebum as a nutritional source. Increased sebum levels can also contribute to increased inflammation in and around the follicle, worsening acne symptoms, contributing to tissue damage and increasing the risk of acne scarring.

Different types of designer Anabolic Steroids have different profiles of androgenic side effects. Anabolic steroids like testosterone and dihydrotestosterone have a relatively high androgenic to anabolic (muscle building) profile, while some synthetics like Oxandrolone tend to have fewer androgenic side effects, relative to the dose.

Sebaceous gland activity is not only regulated by androgens, but also by other compounds that may be used in “performance enhancement” applications. For example, Human Growth Hormone (hGH) is a commonly used muscle building supplement that can also potentially contribute to acne symptoms. Human growth hormone stimulates the production of another growth factor Insulin-Like Growth Factor 1 (IGF-1) which has also been shown to increase sebaceous gland activity.

There are a lot of variables and cross-reacting factors when it comes to Anabolic Steroids and their side effects, like acne. As always, it is strongly recommended that any steroid therapy be done under the supervision of a qualified medical professional. Illicit steroid use can be quite dangerous not only because of the known side effects and legal restrictions (in many countries), but also because of the high incidence rate of poorly labeled, impure and counterfeit product being sold as Anabolic Steroids in the unregulated market.

Treatment of Anabolic Steroid Induced Acne

Obviously, stopping the use of Anabolic Steroids is one solution, although maybe not realistic in all cases. Additionally, stopping use might not actually be enough to completely resolve acne symptoms that were caused by prior Anabolic Steroid use. In most cases of acne (steroid-induced acne included), a central feature of acne is a persistent infection of P. acnes bacteria within hair follicle. Once established, this infection may persist for long after steroid use is stopped. Fortunately, individuals with steroid related acne have many treatment options available to them, including:

RETINOIDS

Isotretinoin Roaccutane Packaging
Isotretinoin (Roaccutane, Accutane)

Both oral retinoids and topical retinoids can help decrease sebaceous gland activity and improve acne symptoms in many individuals. However, there is some research that indicates that oral retinoids (Accutane) may negatively impact athletic performance and recovery times. As a result, oral retinoids are rarely prescribed to competitive athletes who are in active competition. Topical retinoids are effective in some cases, but they tend to be less effective against inflammatory, nodular and cystic forms of acne. Unfortunately, inflammatory acne is fairly common with steroid use.

ANTIBIOTICS

Tetracycline Antibiotic Capsules
Tetracycline Antibiotic Capsules

There are a wide range of topical and oral antibiotics that have been shown to be viable anti-acne treatments. Like topical retinoids, topical antibiotics usually have reduced efficacy against inflammatory forms of acne. Some oral antibiotics have been shown to have both antibacterial and anti-inflammatory properties.

ANDROGEN INHIBITORS

Finasteride Tablets (Propecia)
Finasteride Tablets (Propecia)

While it is unlikely that an individual who is using Anabolic Steroids would be interested in using a systemic androgen inhibitor, there are some topical androgen inhibitors available which have a minimal systemic impact. These topical androgen inhibitors have been used to decrease the effect of anabolic steroids on the skin in a targeted fashion. However, there is not much research on this approach and minimal evidence about its efficacy.

OVER THE COUNTER MEDICATIONS

Over The Counter (OTC) Acne Products
Over The Counter (OTC) Acne Products

For mild cases of steroid induced acne, Over The Counter (OTC) medications that contain benzoyl peroxide, salicylic acid and other antibacterial/keratolytic compounds may be helpful in improving acne symptoms. These medications are generally most effective with mild, non-inflammatory (Acne Types: 1-2) and are less effective against moderate and severe acne symptoms (Acne Types: 3-4).

Common Anabolic Steroids and Their Chemical Structures

Commonly Androgenic Steroids
Common Anabolic Steroids
Chemical Structures of Common Anabolic Steroids (Fragkaki)
Chemical Structures of Common Anabolic Steroids (Fragkaki)

References

A league of their own: demographics, motivations and patterns of use of 1,955 male adult non-medical anabolic steroid users in the United States. Cohen, et al. 2007.
Adverse health effects of anabolic androgenic steroids. Amsterdam, et al. 2010.
Anabolic steroid abuse: Psychiatric and physical costs. Talih, et al. 2007.
Pharmacology of anabolic steroids. Kicman. 2008. 
Social capital: Implications from an investigation of illegal anabolic  steroid networks. Maycock, et al. 2007.
Structural characteristics of anabolic androgenic steroids contributing to binding to the androgen receptor and to their anabolic and androgenic activities: Applied modifications in the steroidal structure. Fragkaki, et al. 2009. 
Control of Human Sebocyte Proliferation in Vitro by Testosterone and 5-DHT is Dependent on the Localization of the Sebaceous Glands. Akamatsu, et al. 1992.

How Do Acne Scars Form?

Boxcar Atrophic Acne Scars on Cheek

Acne scars are the result of tissue damage caused by inflammatory acne.

How Do Acne Scars Form?

Type 4 Acne on Face
Type 4 Acne is Likely to Cause Acne Scars

The vast majority of acne scars are caused by from persistent cases of inflammatory acne affecting the same area of skin. Individuals who suffer from frequent nodular and cystic acne outbreaks (Acne Types: 3-4) are at a very high risk of developing permanent acne scarring. This is particularly true when a region is affected by overlapping acne outbreaks, with no opportunity for the skin to completely heal between outbreaks.

Progression to Inflammatory Acne and Tissue Damage
Progression to Inflammatory Acne and Tissue Damage

When an individual experiences persistent outbreaks of severe inflammatory acne, significant regions of the affected skin and underlying tissue can be damaged. Acne is an inflammatory process that usually involves an infection caused by bacteria (eg. Propionibacterium acnes). The inflammation that occurs during  severe acne prevents the body from mobilizing the cells and materials necessary for the normal healing process that is required to repair the skin. In this situation, the original (healthy) tissue can be replaced by fibrous scar tissue.

The Role of Inflammation in Acne Scarring

What many people may not realize is that acne scarring is primarily due to the body’s own immune response to infection, and not the infection itself. A major component of inflammatory acne is the migration of white blood cells to the hair follicle, sebaceous glands and surrounding tissue. These white blood cells compose much of the “pus” that comes out when you pop a zit.

White Blood Cells
White Blood Cells

The white blood cells that make up the pus in acne pimples, nodules and cysts are not uniform. Instead the pus contains a mixture of many different sub-types of white blood cells, such as macrophages, neutrophils, dendritic cells, T cells, granulocytes, mast cells and others. Neutrophils are one of the body’s front-line defenses against infection and these cells are usually the most abundant white blood cells in an acne lesion.

Many of the white blood cells (and especially neutrophils) produce powerful degradative enzymes that can damage health tissue. These cells also produce inflammatory molecules, super-oxides and free radicals. These weapons are designed to help neutralize pathogens and foreign invaders, but they can also cause damage to the surrounding healthy tissue. In inflammatory acne, the damage caused by these white blood cells can actually cause the underlying bacterial infection to spread, leading to more inflammation and tissue damage. This can create a vicious, self-fulfilling cycle of tissue damage that leads to permanent acne scars.

Infected and Inflamed Hair Follicle (Honcharu)
Infected and Inflamed Hair Follicle (Honcharu)

When it comes to scarring, perhaps the most important type of white blood cell is the neutrophil. The neutrophil is one of the first responders to the infected follicle, and can accumulate in great numbers. Neutrophils are kind of like the suicide bombers of the cellular world. When they reach the site of infection they can undergo apoptosis (controlled suicide) and degranulation, which releases many anti-microbial molecules, DNA and proteases into environment. These proteases that can cause tremendous damage to the surrounding tissue, which ultimately results in scarring. These proteases digest the elastin and collagen matrix that provides support and elasticity to the skin.

Health skin is supported by a complex matrix (scaffolding) that provides structural support and nutrients to the skin surface. When skin is damaged, this matrix helps guide the healing process. Without this matrix to guide healing, the body has a very difficult time properly repairing and re-creating the damaged tissue. In cases of persistent infection and inflammation, the body is not able to repair the matrix fast enough to keep up with the damage. In these cases, the body begins to build scar tissue, which is simple and tough. The scar tissue can permanently replace the more complex and delicate healthy matrix. This process underlies not only the formation of acne scars, but of other diseases marked by chronic inflammation, such as chronic obstructive pulmonary disorder (emphysema) and rheumatoid arthritis.

The Structure of Scar Tissue

Normal Collagen Matrix - Stained Blue (Lee)
Normal Collagen Matrix – Stained Blue (Lee)

Scar tissue is composed largely of collagen, which is the same material that comprises much of a healthy sub-cutaneous matrix. However, unlike the healthy matrix – which is a complex, spacious and interconnected web of collagen and other proteins – the collagen in scar tissue is much different. In scar tissue, the collagen becomes tightly bundled and tends to line up in a single direction, instead of the original, interconnected web pattern.

In scar tissue there is much less open space than healthy tissue, and many of the essential accessory proteins and molecules that are essential for the maintenance of healthy skin are absent. This alignment of the collagen fibers and their closely packed arrangement creates a denser, less elastic tissue. In addition, scar tissue becomes impermeable to migration by many cell types, preventing the formation of blood vessels and a regrowth of complex structures, such as hair follicles and sweat glands. This is why scar tissue is generally monotone, feels tough and dense to the touch, and is hairless. It also explains why the body has such a difficult time replacing scar tissue with healthy tissue.

Repairing Scar Tissue

Once scar tissue has been generated at a site of injury, it is relatively permanent without medical intervention. In some cases, the body will gradually replace some scar tissue with the healthy tissue, but this process is so slow that is largely irrelevant. The single best treatment for acne scarring, is to prevent it in the first place. This means aggressively attacking the infection and treating the inflammation as it arises.

Complete C02 Laser Resurfacing of Acne Scars
Complete C02 Laser Resurfacing of Acne Scars

Fortunately, there are many different treatments available to help repair acne scar damage. The ideal type of treatment is largely dependent on the specific types of acne scarring. Acne scar treatment generally involves either surgically removing the scar tissue, or breaking it apart with laser, heat or surgical treatments. Light and Laser treatments can be very effective treatments for many different kinds of acne scars. Invasive and non-invasive surgical treatments can also be very helpful. Topical Retinoids may also be helpful for very mild acne scars and uneven skin tone.

References

Physiopathology of acne vulgaris: recent data, new understanding of the treatments. Pawin, et al. 2004.
Topical ALA Photodynamic Therapy for the Treatment of Acne Vulgaris. Hongcharu, et al. 2000.
Human b Defensin-1 and -2 Expression in Human Pilosebaceous Units: Upregulation in Acne Vulgaris Lesions. Chronnell, et al. 2001.
A prospective, randomized, placebo-controlled, double-blinded, and split-face clinical study on LED phototherapy for skin rejuvenation: Clinical, profilometric, histologic, ultrastructural, and biochemical evaluations and comparison of three different treatment settings. Lee, et al. 2007.

Sebaceous Glands

Sebaceous Gland High Magnification

Sebaceous glands produce and secrete sebum, which is responsible for moisturizing and protecting skin and hair. Sebaceous glands are essential components of healthy skin. Damaged or malfunctioning sebaceous glands contribute to many dermatological conditions, including acne vulgaris.

Structure of the Sebaceous Glands

Hair Follicle, Sebaceous Glands and Sebum (Wikipedia)
Hair Follicle, Sebaceous Glands and Sebum (Wikipedia)

Sebaceous glands are clusters of specialized cells in the skin. These specialized cells are called sebocytes. Sebocytes are responsible for the synthesis and secretion of sebum. Sebum is a complex blend of fatty acids, waxes, lipids and other molecules that are responsible for moisturizing, lubricating and protecting the skin.

Sebocytes are similar to adipose cells (fat cells) because they accumulate large amounts of fats and lipids. But unlike adipose cells, sebocytes do not store energy. Rather, like true patriots, they sacrifice themselves for the greater good and undergo apoptosis (commit suicide). The death of the sebocyte releases the sebum stored within the cell and this sebum is exported through the hair follicle to the skin surface. Once at the skin surface, the sebum then diffuses into the epidermis where it moisturizes and protects the tissue.

Sebaceous Gland Magnified and Sebum Lipids Labeled with Fluorescent Dye (Smith-and-Zouboulis)
Sebaceous Gland Magnified and Sebum Lipids Labeled with Fluorescent Dye (Smith-and-Zouboulis)

Sebaceous glands are composed of two main types of sebocyte cells – Peripheral Sebocytes and Central Sebocytes. Peripheral Sebocyte Cells (PCs) line the outer edge of the sebaceous gland. Peripheral sebocytes are where the cellular reproduction happens, and from where the sebaceous gland originates and grows. Peripheral sebocytes accumulate relatively little sebum compared to their more mature counterpart, Central Sebocyte Cells (CCs). Central sebocytes originate from proliferating peripheral sebocytes.

As central sebocytes mature, they migrate from the edges to the center of the sebaceous gland. During this process they begin to synthesize and accumulate large reserves of sebum, which they store in specialized storage structures inside the cell, called vacuoles. As they continue to mature, they migrate towards the hair follicle. When completely mature sebocytes reach the follicle opening, they undergo cellular suicide and spill their contents (sebum) into the follicle. This sebum then travels up the follicle to the surface of the skin, where it is essential for the maintenance of the epidermis.

Sebaceous Glands and Acne

Sebaceous Hyperplasia
Sebaceous Hyperplasia

Sebaceous glands can contribute to the development of acne in several ways. One of the most common problems faced by acne sufferers involves overactive sebaceous glands and sebaceous hyperplasia (enlarged sebaceous glands). These conditions can lead to an overproduction of sebum. Excess sebum can facilitate the growth of bacteria (eg. Propionibacterium acnes) that contribute to acne symptoms. These bacteria can utilize sebum as a food source and large food supplies encourage bacterial growth.

Excess sebum production by overactive sebaceous glands can also cause the formation keratinized plugs (clogged pores) that block the follicle and spur the development of inflammatory lesions. Sebum itself and the byproducts of its breakdown can also be comedogenic themselves.

Sebaceous Glands and Hormones

Testosterone is an Androgen Hormone
Testosterone is an Androgen Hormone

Androgen (male) hormones stimulate the growth and activity of the sebaceous glands. Hormonal changes are largely responsible for the well documented increase in acne rates that occurs during adolescence, particularly among males. Women with elevated androgen levels can also experience problems with androgen-dependent sebaceous hyperplasia. Excessive levels of androgen hormones can be treated with androgen inhibitors, which suppress their effects. Sebaceous glands also appear to respond to non-androgen hormones, like Insulin Growth Factor (IGF), a hormone that has been loosely tied to milk consumption.

Sebaceous Glands and Retinoids

Retinoids are a class of acne treatment that can reduce the activity of sebaceous glands. When retinoids comes into contact with sebocytes, it initiates a cascade of changes that dramatically alter the growth pattern of sebocytes. Retinoids causes sebaceous glands to decrease in size and reduces their growth rate, resulting in dramatically decreased sebum production. In some cases, treatment with retinoids can decrease the production of sebum by up to 90%.

Isotretinoin (Roaccutane) 20mg Capsules
Isotretinoin (Roaccutane)

Retinoids can also affect the proliferation of other types of cells. The broad activity of retinoids on a diverse range of cells contributes to some of their potentiatl side effects. The most dangerous side effect of retinoid treatment is potential damage to a developing fetus. Retinoids dramatically disrupt normal embryonic development and leads to severe birth defects. For this reason, oral retinoids (eg. Isotretinoin/Accutane) are tightly controlled in many countries, particularly for women.

Retinoids are available in both oral and topical formulations. Isotretinoin (Accutane) is generally the only retinoid available as an oral treatment. Isotretinoin, Tretinoin, Adapalene and Tazarotene are all retinoids that are available as topical treatments. Topical retinoids tend to be less effective acne treatments than oral retinoids, but have fewer side effects.

Additional Treatments for Sebaceous Hyperplasia

ALA Pretreatment for Photodymanic Therapy of Sebaceous Hyperplasia
ALA Pretreatment for Photodymanic Therapy of Sebaceous Hyperplasia

Emerging therapies that utilize Light and Laser Treatments are becoming increasingly popular options for dealing with problematic sebaceous glands. Specialized Photodynamic Therapy (PDT) and Diode Lasers can be used to specifically target, damage and destroy sebaceous glands. While these treatments can be quite expensive and incompletely effective, their development offers the promise of additional treatments for acne sufferers.

References

Sebaceous Gland Lipids: Friend or Foe? Smith, et al. 2008.
Sebaceous Gland Receptors. Zouboulis. 2009.
Differentiation of the Sebaceous Gland. Niemann. 2009.
The Sebocyte Culture: A Model to Study the Pathophysiology of the Sebaceous Gland in Sebostasis, Seborrhoea and Acne. Zouboulis, et al. 2008.
The Role of Specific Retinoid Receptors in Sebocyte Growth and Differentiation in Culture Kim, et al. 1999.
Sebaceous Gland Lipids Picardo, et al. 2009.
Isotretinoin Revisited: Pluripotent Effects on Human Sebaceous Gland Cells Zouboulis. 2006.

Sebum

Sebaceous Gland High Magnification

What is Sebum?

Sebum is a naturally occurring substance that moisturizes, lubricates and protects the skin and hair. Sebum is produced by the sebaceous glands of mammals. Healthy sebum production is essential for the integrity and normal function of the skin as a protective organ. Sebum is also an important source of energy (food) for acne-causing Propionibacterium acnes bacteria.

Human skin is composed of three primary layers: the stratum corneum, the epidermis, and the dermis. The outermost layer of the skin, the stratum corneum, functions as the primary barrier to the external environment, preventing water loss and the invasion of microorganisms. Sebum is secreted to the stratum corneum from the sebaceous glands and helps maintain an effective, hydrophobic barrier.

The chemical composition of sebum and the rate of sebum production varies from individual to individual, and can even vary depending where on the body the sebum is produced. Normal sebum levels help to maintain healthy skin, but abnormal sebum production or composition can contribute to a variety of diseases, including acne.

Acne symptoms are often associated with sebum overproduction, which can increase the incidence of clogged pores, stimulate inflammation, provide nutrients for bacterial growth. Overproduction of sebum is generally the result of excessive growth and activity of the sebaceous glands. Overactive sebaceous glands and sebum overproduction can be caused by many factors, such as hormones, genetics, stress and environmental stimuli.

The Composition of Sebum

Composition of Human Sebum
Composition of Human Sebum

Sebum is a complex mixture of naturally produced fats, oils, waxes, cholesterols and other molecules. It is important to point out that the fats and oils present in sebum do not originate directly from the fats and oils consumed in the diet. Rather, sebum is manufactured and stored by the sebaceous glands under the direction of a highly specialized biological process.

Most mammals (but not whales and dolphins) produce some sort of sebum, and each animal has its own unique blend. In addition to sebaceous glands and sebum, there are other structures in the skin that produce a sebum-like mixture called “epidermal lipids”.

Differences in Sebum Composition Between Normal and Acne Prone Skin (Pappas)
Differences in Sebum Composition Between Normal and Acne Prone Skin (Pappas)

Human sebum is composed primarily of glycerides, free fatty acids, wax esters and squalenes. Glycerides are more commonly known as “fats” and are molecules of two or three free fatty acids connected together by a glycerol backbone. Free fatty acids are the building blocks of glycerides and other molecules. They are composed of a polar head group and a non-polar (aliphatic tail). Wax esters are molecules composed of fatty acids linked to fatty alcohols by an ester bond. Squalenes are hydrophobic chains of carbon atoms that serve as the basic building block for naturally occuring steroids and other types of signal molecules.

The Role of Sebum in Acne Vulgaris

Several research studies have found a direct relationship between increased sebum secretion and increased acne symptoms. People with sebaceous gland disorders (e.g. sebaceous hyperplasia) that lead to very high sebum levels often have severe forms of acne and other skin diseases. However, there are several possible explanations for how sebum production may contribute to acne, and there is not unanimous agreement between experts when it comes to explaining this relationship.

Sebaceous Gland Hyperplasia (Smith)
Sebaceous Gland Hyperplasia (Smith)

The most common explanation for why elevated sebum production leads to acne symptoms is that increased sebum production leads to increased follicular plugs (clogged pores). Clogged pores create an low oxygen (hypoxic) environment that supports the growth of acne-causing P. acnes bacteria. Sebum is also a source of food for P. acnes bacteria. The accumulation of sebum within plugged follicles provides ideal growing conditions for P. acnes bacteria and can lead to large numbers of these bacteria growing in the skin.

Research has also found that sebum itself can lead to increased inflammation. Byproducts of the sebum metabolism may cause the accumulation of molecules that trigger an inflammatory immune response. It is possible that this mechanism is at work in some individuals with inflammatory acne.

Research has also shown that people with abnormally high sebum production tend to make sebum that has a different composition than the sebum from people with normal levels. Apparently, people with acne tend to have decreased levels of free fatty acids, but increased levels of glycerides and squalene. Some scientists have proposed that these compositional changes play a role in the development of acne symptoms..

The Regulation of Sebum Production

The proliferation of sebaceous glands and production of sebum is directly regulated by a complex system of hormones and other cellular signals. Going deeper, these hormonal signals are controlled by an even more complex balance that includes genetics, environmental conditions, metabolic conditions, stress, diet, injury and many other factors. Despite this extraordinary complexity, scientists have begun to unravel the central relationships in sebaceous gland biology.

Several of the central factors that control sebum production have been identified and are currently being investigated by scientists. The major regulators of sebaceous gland activity include:

Androgens

Androgens Drive Muscle Growth
Androgens Drive Muscle Growth

Androgens are male sex hormones, like testosterone. Acne symptoms commonly develop in males during adolescence, when levels of androgen hormones in the body are their highest. Androgens drive the development of many male characteristics, like muscle and body hair growth. They also stimulate the proliferation of sebaceous glands, particularly those located on the face, chest and upper back.

Individuals with excessively high levels of androgen hormones tend to have higher levels of sebaceous gland proliferation, sebum production and acne vulgaris. Women with elevated androgen levels tend to have higher levels of acne and hirsuitism (excess body hair growth). The effect of androgens on sebaceous gland activity is also why the use of anabolic steroids, which increase androgen levels, can cause acne symptoms.

Estrogens

Estrogen Molecule
Estrogen Molecule

Estrogens are female sex hormones. In most cases, estrogens antagonize (suppress) the effects of androgen hormones. This relationship partially explains why acne symptoms tend to change over the course of a woman’s menstrual cycles, or during and after pregnancy. Men do not usually produce significant levels of estrogen hormones. Estrogens may also directly modulate sebaceous gland activity, although this relationship is not well studied.

Insulin-Like Growth Factor 1 (IGF-1)

IGF-1 is a protein hormone that is produced in the liver and is similar in structure to insulin. Researchers have reported that high IGF-1 levels correlate with elevated sebum production. Levels of IGF-1 tend to be highest during adolescence. Since insulin is similar in structure to IGF-1, it is possible that elevated levels of insulin could cause increased sebum production.

Insulin levels are often elevated in individuals who consume a high glycemic diet (high sugar/carbohydrate), or who have Type 2 diabetes. This relationship could explain the observed correletion between high glycemic diets, obesity and increased incidence of acne vulgaris. Increased IGF-1 has also been linked to milk consumption, although these studies are not necessarily conclusive. IGF-1 hormone production is stimulated by human growth hormone (hGH).

Retinoids

Retinoids are intercellular signalling molecules that are derived from Vitamin A. Retinoid is the generic name for a diverse class of related molecules that play essential roles in many human biological systems, including development of the human embryo. The proliferation of sebaceous glands and the production of sebum is directly controlled by specific retinoid signal molecules. Accutane (Isotretinoin, 13-cis-retinoic acid) is a retinoid that is a powerful anti-acne drug. Binding of Isotretinoin molecules to specialized receptors on the surface of sebocyte cells causes them to slow down their growth and sebum production. The natural balance of different retinoids in the body has a direct impact on sebaceous gland activity.

Environmental Conditions

Seasonal Variation in Sebum Production (Youn)
Seasonal Variation in Sebum Production (Youn)

Recent research has shown that sebum secretion levels change in response to seasonal and environmental changes. While the changes are not drastic, researchers observed that sebum secretion levels were highest during the summer. These changes may be due to the increased fluidity of sebum in warmer conditions, or something else entirely.

Generally speaking, acne sufferers tend to observe an improvement in their acne symptoms during the summer, although this could be more directly related to factors such as UV light exposure or stress levels, than to sebum production. Overall, the research indicates that sebum production is modulated by environmental conditions, although it is less clear whether these normal fluctuations play a role in the development of acne or other skin conditions.

Stress

Stressed Out
Stress

Several research studies have reported that there is a direct correlation between stress and increased acne symptoms. However, other research studies have found that stress does not appear to increase the levels of sebum production. While it is well understood that stress can modulate levels of certain hormones, like cortisol, it does not appear that these pathways directly impact sebaceous gland activity.

Treatments for Excessive Sebum Production

For acne patients with abnormally high levels of sebum production, decreasing sebum production will often improve acne symptoms. There are several medications available that can decrease sebaceous gland activity and sebum production, including:

Retinoids

Retinoids are the most common course of treatment for individuals with hyperactive sebaceous glands and abnormally high sebum production. Retinoids can be an effective acne treatment for many people. Retinoids cause side effects related to decreased sebum production, such as dry and sensitive skin.

Isotretinoin (Roaccutane) 20mg Capsules
Isotretinoin (Roaccutane)

The oral retinoid Isotretinoin (Accutane) is a potent anti-acne medication that can dramatically reduce sebum production. For many individuals, treatment with isotretinoin can lead to significant, long-lasting improvement in their acne symptoms. However, Accutane can have significant side effects, causes severe birth defects in pregnant women, and is tightly controlled in many countries.

Topical retinoid medications are commonly used to treat acne and other skin conditions. Popular topical retinoids include tretinoin (Retin-A), adapalene (Differin), tazarotene (Tazorac) and isotretinoin (Isotrex). These treatments also decrease sebum production, although the effect is often less dramatic than that of oral retinoids.

Retinoids are also used in Naturopathic acne treatments. Retinoids are naturally present in some plant extracts, such as Rose Hip Seed Oil.

Androgen Inhibitors

Spironolactone 25mg Tablets
Spironolactone 25mg Tablets

Androgen Inhibitors can block the activity of the androgen hormones that stimulate sebum production.  Androgen inhibitors like spironolactone (Aldactone) and cyproterone (Androcur) can partially block the effects of androgen hormones and decrease sebaceous gland activity. Androgen Inhibitors are available in both oral and topical formulations.

Hormonal Contraceptive medications can also block the effect of androgen hormones. Both anti-androgen medications and birth control medications are usually reserved for use in females, because their effects can disrupt the normal function of the male hormone system.

Light and Laser Treatments

Photodynamic Therapy (PDT) Acne Treatment
Photodynamic Therapy (PDT)

Light and Laser Treatments have become increasingly popular for the treatment of acne and other skin disorders. Certain light and laser treatments, like Photo Dynamic Therapy (PDT) and Diode Laser Therapy, can be used to directly target the sebaceous glands. Damaging the sebaceous glands with laser treatments can decrease the production of sebum at the treatment site. Depending on the specific type of laser treatment, these effects can be semi-permanent.

References

Transient Receptor Potential Vanilloid-1 Signaling as a Regulator of Human Sebocyte Biology. Toth, et al. 2009.
Comparative Chemistry of Sebum. Nikkari. 1974.
Comprehensive analysis of the major lipid classes in sebum by rapid resolution high-performance liquid chromatography and electrospray mass spectrometry. Camera, et al. 2010.
Quantitative evaluation of sebum lipid components with nuclear magnetic resonance. Robosky, et al. 2008.
Sebaceous gland lipids. Picardo, et al. 2009.
Variation in Sebum Fatty Acid Composition Among Human Adults. Green, et al. 1984.
Sebaceous gland lipids: friend or foe? Smith, et al. 2007.
Sebum analysis of individuals with and without acne. Pappas, et al. 2009.
Does facial sebum excretion really affect the development of acne? Youn, et al. 2005.
Sebum output as a factor contributing to the size of facial pores. Roh, et al. 2006.
Comparison of sebum secretion, skin type, pH in humans with and without acne. Kim, et al. 2006.
Can sebum reduction predict acne outcome? Janiczek-Dolphin, et al. 2010.
Human Neutrophils Convert the Sebum-derived Polyunsaturated Fatty Acid Sebaleic Acid to a Potent Granulocyte Chemoattractant. Cossette, et al. 2008.
Peroxisome Proliferator-Activated Receptors Increase Human Sebum Production. Trivedi, et al. 2006.
Sebum Free Fatty Acids Enhance the Innate Immune Defense of Human Sebocytes by Upregulating b-Defensin-2 Expression. Nakatsuji, et al. 2010.
Control of Human Sebocyte Proliferation in Vitro by Testosterone and 5-DHT is Dependent on the Localization of the Sebaceous Glands. Akamatsu, et al. 1992.
Differentiation of the sebaceous gland. Niemann. 2009.
Correlation of facial sebum to serum insulin like growth factor-1 (IGF-1) in patients with acne. Vora, et al. 2008.
The Role of Specific Retinoid Receptors in Sebocyte Growth and Differentiation. Kim, et al. 2000.
The Effect of Marked Inhibition of Sebum Production with 13-Cis-Retinoic Acid on Skin Surface Lipid Composition. Strauss, et al. 1980.
Regional and seasonal variations in facial sebum secretions: a proposal for the definition of combination skin type. Youn, et al. 2005.
Study of Psychological Stress, Sebum Production and Acne Vulgaris in Adolescents. Yosipovitch, et al. 2007.

The Antibiotic Families

Clindamycin Capsules

There are many different families of antibiotics. Each antibiotic family targets bacteria in a unique way. Each antibiotic family tends to be more effective against certain types of bacteria, and less effective against others.

Antibiotics from several different families are used for the treatment of acne. The antibiotic families most commonly used in acne treatment are Macrolides, Tetracyclines, Pleuromutilins, Sulfonamides and Quinolones. Antibiotics can be used applied topically or ingested orally. The route of delivery, the ability of an antibiotic to accumulate in the skin and the susceptibility of P. acnes bacteria to an antibiotic all impact the efficacy of a given antibiotic treatment.

For more information about the sensitivity of Propionibacterium acnes (P. acnes) to specific antibiotics, visit our Antibiotic Susceptibility of Propionibacterium acnes page. For more information about the P. acnes bacterium, visit our What Is Propionibacterium acnes? page. Below is a summary of the different antibiotic families that are used in the treatment of acne.

Aminoglycosides

Aminoglycoside Family Members: Gentamicin (Garamycin), Neomycin (Neosporin), Paromomycin (Gabbroral), Tobramycin (Tobrex).
Frequency of Use For Acne Treatment: Uncommon.
General Efficacy as Acne Treatments: Poor.
Frequency of High-Level Antibiotic Resistance: Very Common.

Aminoglycoside antibiotics tend to be ineffective treatments for acne vulgaris. The acne-causing P. acnes bacterium is naturally resistant to most antibiotics in the Aminoglycoside family.

Aminoglycoside antibiotics are modified sugar molecules that are pimarily effective against gram-negative bacteria (P. acnes bacteria are gram-positive). Aminoglycoside antibiotics work by binding to bacterial ribosomes and inhibiting the bacteria’s ability to synthesize new proteins. Aminoglycosides are popular antibiotics for topical first-aid treatments (the primary ingredient in Neosporin is neomycin, an aminoglycoside). Topical aminoglycoside ointments (eg. Neosporin) may help prevent secondary infections of damaged skin and/or popped pimples. Therefore, they may help prevent mild acne scarring and accelerate the healing process.

Aminoglycoside Antibiotics

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Amphenicols

Amphenicol Family Members: Chloramphenicol (Clorin), Thiamphenicol (Biothicol).
Frequency of Use For Acne Treatment: Rare.
General Efficacy as Acne Treatments: Unknown.
Frequency of High-Level Antibiotic Resistance: Rare.

Amphenicols are a family of broad spectrum antibiotics that are used in many topical antibacterial medications, such as opthalmic solutions (eye drops). Amphenicols work by disrupting the ability of bacteria to synthesize new proteins. Antibiotic susceptibility testing indicates that P. acnes bacteria tend to be moderately susceptible to Amphenicols, and P. acnes bacteria with high-level resistance to Amphenicols are rare.

Amphenicols are rarely used for the treatment of acne. But topical formulations of Amphenicols (eg. Chloramphenicol) may be a useful acne treatment for some individuals. Topical Amphenicols may complement other types of acne treatments.

Amphenicol Antibiotics

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Cephalosporins

Cephalosporin Family Members: Cefaclor (Ceclor), Cefadroxil (Duricef), Cefdinir (Omnicef), Cefixime (Suprax), Cefpodoxime (Cefpo), Cefprozil (Cefzil), Cefradine (Cefradune), Ceftibuten (Cedax), Cephalexin (Keflex).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: OK.
Frequency of High-Level Antibiotic Resistance: Uncommon.

Cephalosporins are occasionally used as oral antibiotic treatments for moderate to severe acne symptoms (Acne Types: 2-4). Many individuals with acne have reported positive results from treatment with various Cephalosporin antibiotics. But not all acne patients achieve significant improvement with Cephalosporins.

Cephalosporins are type of beta-lactam antibiotic and they are structurally-related to the Penicillins. Cephalosporins kill bacteria by disrupting their cell walls via inhibition of peptidoglycan layer assembly. In contrast to Penicillins, Cephalosporins are effective against a broader range of bacteria and are more resistant to a bacterial antibiotic-resistance enzyme called Penicillinase. In antibiotic susceptibility testing, Cephalosporins were effective against P. acnes bacteria, but they tend to be less toxic to P. acnes than Penicillins.

Cephalosporin Antibiotics

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Fusidic Acid

Fusidic Acid Family Members: Fusidic Acid (Fucidin).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: OK.
Frequency of High-Level Antibiotic Resistance: Uncommon.

Fusidic Acid is an antibiotic that prevents bacteria from synthesizing proteins by disrupting the function of a bacterial protein, Elongation Factor G (EF-G). Fusidic acid is available in oral and topical formulations. Topical Fusidic Acid is the form of this antibiotic that is generally used for the treatment of acne.

Antibiotic susceptibility testing indicates that the acne-causing P. acnes bacterium tends to be moderately susceptible to Fusidic Acid. Many patients have reported positive results with the use of topical Fusidic Acid. Fusidic Acid is generally used in combination with a complementary antibiotic.

Fusidic Acid Antibiotics

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Lincosamides

Lincosamide Family Members: Clindamycin (Cleocin).
Frequency of Use For Acne Treatment: Very Common.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Occasional (Increasing).

One member of the Lincosamide family, Clindamycin, is frequently used for the treatment of acne. Clindamycin is generally used as a topical medication, but oral versions of this antibiotic are also available. Topical Clindamycin can be an effective treatment for mild to moderate acne symptoms (Acne Types: 1-3).

Lincosamides are structurally related to the Macrolide family of antibiotics. Lincosamides work by binding to the bacterial 23S ribosome, which inhibits the ability of the bacteria to synthesize new proteins. Lincosamides are generally very toxic to P. acnes bacteria, but Lincosamide-resistant P. acnes bacteria are becoming increasingly common. Research reports indicate that Clindamycin-resistant P. acnes bacteria are especially common in the United States and Europe.

Lincosamide Antibiotics

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Macrolides

Macrolide Family Members: Azithromycin (Zithromax), Clarithromycin (Biaxin), Dirithromycin (Dynabac), Erythromycin (E-Mycin), Josamycin (Josalid), Pristinamycin (Pyostacine), Roxithromycin (Roximycin), Spiramycin (Spirex), Telithromycin (Ketek).
Frequency of Use For Acne Treatment: Common.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Occasional (Increasing).

Macrolides are a diverse class of antibiotics that includes several medications that are commonly used for the treatment of acne. Macrolides work by preventing bacteria from synthesizing new proteins. They do this by binding to a bacterial enzyme called Peptidyltransferase and/or binding to the bacterial 50S ribosome subunit. Macrolides are structurally related to Lincosamide antibiotics.

Macrolides are commonly used to treat infections caused by gram-positive bacteria. Topical macrolide antibiotics (eg. Erythromycin) are a very common treatment for acne, but oral Macrolides are also widely used. Antibiotic susceptibility testing indicates that Macrolides are usually very toxic to acne-causing P. acnes bacteria. However, Macrolide-resistant P. acnes bacteria are becoming increasingly common in many areas. Current research now indicates that a significant proportion of acne-associated P. acnes bacteria in the United States and Europe have now acquired some level of resistance to Macrolide antibiotics.

Macrolide Antibiotics

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Nitroimidazoles

Nitroimidazole Family Members: Metronidazole (Flagyl).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Poor.
Frequency of High-Level Antibiotic Resistance: Very Common.

Nitroimidazole antibiotics are used to treat infections that are caused by both bacteria and parasites. Nitroimidazoles work by disrupting the ability of microbes to synthesize new DNA.

Metronidazole is the only member of the Nitroimidazole family that is routinely used in the treatment of acne. Topical Metronidazole is also a common treatment for Rosacea. Antibiotic susceptibility testing indicates that P. acnes bacteria are naturally resistant to Metronidazole. However, many individuals with acne report improvements in their symptoms following use of Metronidazole. These improvements may be the result of Metronidazole’s ability to kill other types of bacteria that can contribute to acne symptoms (eg. S. aureus).

Nitroimidazole Antibiotics

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Oxazolidinones

Oxazolidinone Family Members: Linezolid (Zyvox) and Tedizolid (Sivextro).
Frequency of Use For Acne Treatment: Rare.
General Efficacy as Acne Treatments: Unknown.
Frequency of High-Level Antibiotic Resistance: Rare.

Oxazolidinones are a relatively new class of antibiotics that are used to treat certain types of inections caused by gram-positive bacteria. Oxazolidinones prevent bacteria from synthesizing new proteins by preventing N-formylmethionyl-tRNA from binding to the bacterial ribosome.

Oxazolidinones are rarely used in the treatment of acne. However, antibiotic susceptibility testing indicates that they are active against the acne-causing P. acnes bacteria. These antibiotics may become more widely used as acne treatments in the future.

Oxazolidinone Antibiotics

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Penicillins

Penicillin Family Members: Amoxicillin (Amoxil), Ampicillin (Polycillin), Ampicillin + Clavulanic Acid (Augmentin), Cloxacillin (Cloxapen), Dicloxacillin (Diclocil)Flucloxacillin (Floxapen), Penicillin G (BenzylPenicillin), Penicillin V (Phenoxymethylpenicillin).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Rare.

Penicillin was discovered in 1920s by the Nobel Prize winning scientist Alexander Fleming. The discovery of Penicillin revolutionized the treatment of bacterial infections and initiated the modern era of antibiotics. Penicillins are beta lactam antibiotics that are structurally related to the Cephalosporins. Penicillin antibiotics work by damaging the cell wall of susceptible bacteria. They are most effective against gram positive bacteria, a group that includes the acne-causing P. acnes bacterium.

Penicillins are available in topical and oral formulations, both of which are occasionally used for the treatment of acne. Individuals with acne have generally reported positive results from treatments with Penicillin family antibiotics. Antibiotic susceptibility testing has shown that most P. acnes bacteria are extremely sensitive to Penicillins.

Penicillin Antibiotics

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Pleuromutilins

Pleuromutilin Family Members: Retapamulin (Altabax).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Rare.

Pleuromutilins are new class of antibiotics that are used to treat certain types of infections caused by gram-positive bacteria. Pleuromutilins work by preventing bacteria from synthesizing new proteins via inhibition of a bacterial enzyme called Peptidyl Transferase.

Antibiotic susceptibility testing indicates that P. acnes bacteria are highly sensitive to Pleuromutilin antibiotics, such as Retapamulin. Retapamulin is the only antibiotic in this family that is currently approved for human use. Retapamulin is used as a topical treatment for several kinds of skin infections, including acne. Patient reports and clincal research indicate that topical Retapamulin can significantly improve acne symptoms for most patients. The use of topical Retapamulin as a treatment for acne is likely to become more common as this medication becomes more widely available.

Pleuromutilin Antibiotics

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Quinolones

Quinolone Family Members: Ciprofloxacin (Cipro), Gatifloxacin (Tequin), Gemifloxacin (Toplon), Levofloxacin (Levaquin), Moxifloxacin (Avelox), Nadifloxacin (Nadixa), Nalidixic Acid (Wintomylon), Norfloxacin (Norflox), Ofloxacin (Floxin) and Sparfloxacin (Zagam).
Frequency of Use For Acne Treatment: Uncommon.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Rare.

Quinolones are a class of broad-spectrum antibiotics that were discovered in the 1960s. Quinolones inhibit bacterial growth by preventing bacteria from reading and duplicating their DNA. Quinolones are effective against both gram-negative and gram-positive bacteria.

Quinolones are commonly used in combination with other antibiotics. They are rarely used for long term treatments or prophylaxis. This is because bacteria can develop resistance to Quinolones easire than they can to most other antibiotics. Quinolones also tend to have higher rates of side effects than other antibiotics.

Laboratory testing indicates that P. acnes bacteria are generally susceptible to most antibiotics in the Quinolone family. However, Quinolones are not commonly used for the treatment of acne vulgaris. Patient reports indicate that oral Quinolones can improve acne symptoms in many patients, at least temporarily. Most Quinolones are only available in oral formulations, but there is one fairly new Quinolone for topical use that is gaining some buzz – Nadifloxacin. Topical Nadifloxacin is not available in all countries, but several studies suggest that this medication can significanly improve acne symptoms in some individuals. Because it is administered topically, Nadifloxacin has a much better safety profile than most oral antibiotics.

Quinolone Antibiotics

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Rifamycins

Rifamycin Family Members: Rifabutin (Mycobutin), Rifampicin (Rifampin), Rifapentine (Priftin).
Frequency of Use For Acne Treatment: Rare.
General Efficacy as Acne Treatments: Unknown.
Frequency of High-Level Antibiotic Resistance: Rare.

Rifamycins were discovered in the 1950’s. Rifamycins work by preventing bacteria from reading their own DNA (they block RNA synthesis). Rifamycins are important components of the combined antibiotic therapies used to treat tuberculosis. Because Rifamycins are an essential part of anti-tuberculosis therapy, their use in the treatment of other infections has been restricted in some places. Antibiotic resistance to Rifamycins tend to develop faster than resistance to other antibiotics.

Antibiotic susceptibility testing indicates that Rifamycins are very toxic to most strains of P. acnes bacteria. However, Rifamycins are rarely used for the treatment of acne vulgaris. Several research and patient reports suggest that Rifamycins (Rifampicin in particular) can be very effective at improving acne symptoms for some individuals. More research is needed on the utility of Rifamycin family antibiotics in the treatment of acne. Rifamycines are generally only available in oral formulations.

Rifamycin Antibiotics

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Sulfonamides

Sulfonamide Family Members: Co-Trimoxazole (Bactrim), Dapsone (Aczone), Mafenide (Sulfamylon), Silver Sulfadiazine (Silvadene), Sulfacetamide (Clenia)Sulfadimethoxine (Albon), Sulfadoxine (Sulphadoxine), Sulfafurazole (Sulfisoxazole), Sulfamethoxazole (SMX) and Sulfathiazole (Sulfatiazol).
Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Good.
Frequency of High-Level Antibiotic Resistance: Rare.

Sulfonamides are a class of antibiotics whose molecules all contain sulfur atoms. They were among the first oral antibiotics to be used in human medicine and their use became widespread in the 1930s. Sulfonamides work by preventing bacteria from synthesizing an essential vitamin, Folate (Vitamin B9).

Antibiotics in the Sulfonamide family are available in many oral and topical formulations. Sulfonamides are also widely used in veterinary medicine. Antibiotic susceptibility testing indicates that ance-causing P. acnes bacteria tend to be moderately susceptible to Sulfonamides. Topical sulfonamides (eg. Dapsone, Mafenide, Silver Sulfadiazine and Sulfacetamide) are occassionally used for the treatment of mild to moderate acne symptoms (Acne Types: 1-3) and many individuals have reported positive results with these medications. Because Sulfonamides have a unique mechanism of action, they can be combined with many other acne medications.

Only one oral Sulfonamide antibiotic is routinely used as an acne treatment – Co-Trimoxazole. Co-Trimoxazole is a combination of two antibiotics Sulfamethoxazole and Trimethoprim. These two antibiotics work synergistically and are substantially more effective in together than either is alone. Co-Trimoxazole is an important acne treatment because it can be very effective for individuals with moderate to severe inflammatory acne (Acne Types: 3-4). However, Co-trimoxazole is not routinely prescribed for the treatment of acne vulgaris in many places. This is primarily the result of two factors. First, allergic reactions to oral Sulfonamides can be more severe than allergic reactions caused by other antibiotics. Second, the use of Co-Trimoxazole as an acne treatment is considered “off-label” in many countries, including the United States. As a result, many physicians do not feel comfortable considering Co-Trimoxazole for the treatment of acne. But for those patients without allergies to Sulfonamides, Co-trimoxazole treatments may yield substantial improvements in difficult-to-treat acne cases.

Sulfonamide Antibiotics

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Tetracyclines

Tetracycline Family Members: Demeclocycline (Declomycin), Doxycycline (Vibramycin), Lymecycline (Tetralysal), Minocycline (Minocin), Oxytetracycline and Tetracycline (Sumycin).
Frequency of Use For Acne Treatment: Very Common.
General Efficacy as Acne Treatments: OK.
Frequency of High-Level Antibiotic Resistance: Common.

Tetracyclines were discovered in the 1940s by the plant scientist Benjamin Duggar. Tetracyclines are a class of broad-spectrum antibiotics that work by inhibiting protein synthesis in susceptible bacteria via disruption of the 30S Ribosome. In the past, Tetracyclines were frequently used for the treatment of many different types of infections. But in the last thirty years, the efficacy of Tetracyclines has decreased substantially due to the spread of Tetracycline-resistant bacteria.

Tetracyclines are the antibiotic family of choice for many dermatologists when treating acne. Oral Tetracyclines are commonly used for the treatment of moderate to severe acne symptoms (Acne Types: 2-4). However, antibiotic susceptibility reports clearly demonstrate that Tetracycline-resistant P. acnes bacteria are common, particularly in certain regions of the world (eg. United States and Europe).

When acne is caused by Tetracycline-susceptible bacteria, treatment with Tetracyclines (particularly Minocycline) can be very effective. But current patient reports and clinical research indicate that Tetracyclines yield little to no improvement in acne symptoms for many individuals. The likely reason why Tetracyclines are so frequently used for the treatment of acne, despite their mediocre efficacy and the prevalence of Tetracycline-resistant P. acnes bacteria, is that many of the prescribing guidelines now in use for the treatment of acne were developed decades ago, when the patterns of antibiotic resistance among P. acnes bacteria were different.

Tetracycline Antibiotics

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Additional Antibiotics

BACITRACIN

Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Unkown.
Frequency of High-Level Antibiotic Resistance: Common.

FOSFOMYCIN

Frequency of Use For Acne Treatment: Rare.
General Efficacy as Acne Treatments: Unkown.
Frequency of High-Level Antibiotic Resistance: Very Common.

GRAMICIDIN

Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Unkown.
Frequency of High-Level Antibiotic Resistance: Common.

MUPIROCIN

Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: Poor.
Frequency of High-Level Antibiotic Resistance: Very Common.

NITROFURANTOIN

Frequency of Use For Acne Treatment: Rare.
General Efficacy as Acne Treatments: Unknown.
Frequency of High-Level Antibiotic Resistance: Rare.

TRIMETHOPRIM

Frequency of Use For Acne Treatment: Occasional.
General Efficacy as Acne Treatments: OK.
Frequency of High-Level Antibiotic Resistance: Rare.

The Antibiotic Susceptibility of Propionibacterium acnes

Bacteria Antibiotic Susceptibility Test Plate (credit - Wikipedia)

Summary

For the past 50 years, physicians and researchers have been screening the susceptibility of Propionibacterium acnes (P. acnes) bacteria to different antibiotics. The results from these studies clearly demonstrate that in many places, P. acnes bacteria are becoming increasingly resistant to certain classes of antibiotics.

In many countries, a significant percentage of the P. acnes bacteria isolated from acne patients are now resistant to the some of the antibiotics that are commonly used in acne treatment (eg. Clindamycin, Erythromycin, Tetracycline, Doxycycline and Minocycline). The patterns of antibiotic resistance among acne-causing P. acnes bacteria tend to vary between countries. These variations are influenced by many factors. Not all of these factors are directly associated with acne vulgaris.

What Does Antibiotic Resistance and Susceptibility Mean?

Not all antibiotics are created equal. The same is true for bacteria. Some types of antibiotics are highly effective against certain types of bacteria, but useless against other types of bacteria. In addition, antibiotic susceptibility and resistance is a dynamic process that is constantly changing. Over time, certain types of bacteria may gain or lose resistance to particular antibiotics. The general trend is that over time, bacterial resistance to commonly-used antibiotics increases, but this is not a uniform process.

Bacteria Antibiotic Susceptibility Test Plate (credit - Wikipedia)
Bacteria Antibiotic Susceptibility Test Plate (Wikipedia)

Antibiotic susceptibility testing is usually conducted by growing bacteria in special petri dishes with small disks that contain known amount of antibiotics. When scientists test the susceptibility of bacteria to different antibiotics, they generally focus on the Minimum Inhibitory Concentration (MIC) of an antibiotic. The MIC is defined as the lowest concentration of an antimicrobial compound that will inhibit the visible growth of a microorganism after overnight incubation.

The Limitations of Antibiotic Resistance Testing

The primary problem with conventional antibiotic resistance testing is that the susceptibility of a bacteria to an antibiotic is often different when it is growing on a petri dish versus when it is growing in the body.

The first reason for these differences are because bacteria adapt to their environment. P. acnes bacteria that is growing in a hair follicle and feeding on sebum from the sebaceous glands has a different metabolic profile than one growing on a petri dish and feeding on a bacterial nutrition supplement. In addition, bacteria can modulate expression of surface proteins, cell wall structures and antibiotic resistance genes in response to changes in their environment. The adaptation of a bacteria to its specific environment can have a profound effect on its susceptibility to a particular antibiotic.

The second major limitation with antibiotic susceptibility testing is that antibiotics are not evenly dispersed throughout the different tissues in the body. Different types of antibiotics tend to accumulate in different tissues. Many antibiotics do not effectively accumulate in the skin, which means that they may not inhibit acne-causing bacteria growing deep inside follicles. Even if a bacteria is highly susceptible to a particular antibiotic in laboratory testing, if that antibiotic does not make it to the site of infection at a sufficient concentration, it is not going to be an effective treatment.

What Causes Antibiotic Resistance?

Examples of How Antibiotic Resistant Bacteria Spread (credit - CDC)
Examples of How Antibiotic Resistant Bacteria Spread (CDC)

A commonly held belief is that the over-use of antibiotics in an outpatient setting and patients that fail to complete their prescribed antibiotic treatments are the primary causes of emerging antibiotic resistance. While these two factors do contribute to the growing incidence of antibiotic resistant infections, they are far from the only causes. Other sources of antibiotic-resistant bacteria include antibiotic use in commercial livestock farming, unsatisfactory hygiene in institutional settings (hospitals, nursing homes, prisons) and HIV/AIDS. For an in-depth discussion of both the mechanisms and causes of antibiotic resistance read – How Do Bacteria Become Resistant to Antibiotics?

The Emergence of Antibiotic Resistant Strains of P. acnes

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

Starting in the 1990’s some popular antibiotics started becoming less effective for the treatment of acne in certain countries. This change was particularly pronounced in places where acne vulgaris was routinely treated with antibiotics (eg. North America and Europe). A 2001 study by Ross, et al examined P. acnes isolated from acne patients and found that the bacteria was much more likely to be resistant to commonly used anti-acne antibiotics than they had been in the past. In particular, they found that most of the bacteria was resistant to Macrolide Family (eg. Erythromycin, Azithromycin, Clindamycin) and Tetracycline Family (Minocycline, Doxycycline) antibiotics. It is unlikely to be a coincidence that these two families of antibiotics include the most commonly used anti-acne antibiotics.

Antibiotic resistance testing clearly indicates that acne-causing P. acnes bacteria are becoming increasingly resistant to the antibiotics commonly used as acne treatments. Particularly in places like Europe and the United States, where the use of antibiotics to treat acne is fairly common, a large percentage of bacteria isolated from acne patients are now show an elevated level of antibiotic resistance. Generally speaking, the data indicates that in Europe, resistance to Macrolide antibiotics is very high, and resistance to Tetracycline antibiotics is also elevated. The situation is similar in the US, but Tetracycline resistance appears to be more common.

The scientific research also clearly shows that some of the antibiotic treatments that have been the mainstay of dermatologists in the fight against acne, are now becoming ineffective. As a result, for patients who have P. acnes infections that are resistant to these common treatments, it may be helpful to explore alternative types of anti-acne medications, such as Retinoids, Hormonal Treatments, Naturopathic Treatments and Light & Laser Therapies.

Antibiotic Resistance and Susceptibility Test Results for Propionibacterium acnes

Scientists have been testing antibiotics against P. acnes bacteria for over forty years. To summarize this history of testing into a single document, we have compiled a composite chart that includes the results of many of these research studies on the antibiotic susceptibility screens of P. acnes bacteria.

How To Read Our Composite Antibiotic Susceptibility Chart:

Many studies use different standards and measurements. We have translated these various results into a simple 1 (Worst) to 5 (Best) scale. The lower the value the LESS effective the antibiotic was in testing. The higher the value the MORE effective the antibiotic was. The average score for each medication is listed on the left hand side of the chart and is color coded (red = least effective, yellow = moderately effective, green = most effective). The average score for each family of antibiotic is also listed next to the name of that family. On the chart itself, a box that is highlighted in red indicates that scientists detected P. acnes bacteria that were highly resistant to that particular antibiotic.