A Call to Limit Antibiotic Use in Acne

With increasing urgency, national and international health authorities are calling for physicians to limit antibiotic use.¹ Generally, physicians are familiar with efforts to reduce antibiotic prescriptions to minimize bacterial resistance, particularly in regards to respiratory infections.² Many may be less familiar with the fact that there is significant antibiotic use in acne,^{3, 4} with patients often taking prolonged courses of antibiotic therapy. Acne affects the vast majority of the world’s population at some time in their lives,⁵ and many clinicians who manage acne patients utilize antibiotics as a primary treatment.^{3, 4} As dermatologists with special interest in acne, we call on our colleagues in medicine to review current information on antibiotic use in acne and prescribe these agents in a judicial manner. We discuss below some of the primary reasons to revise the current prescription pattern.

First, Propionibacterium acnes (the primary bacterial target) is only one of the 4 pathogenic factors in acne.^{5, 6} Combination therapy involving a topical retinoid plus an antimicrobial is the recommended first-line approach, based on the premise that it is most efficacious to target multiple pathophysiologic mechanisms and the results of numerous clinical studies showing improved efficacy.^{*5, 6} By tailoring the choice of antimicrobial and duration of antibiotic use, this combination approach can be utilized for almost all patients with acne, providing results that are faster and superior to antibiotic therapy alone.^*4,5

Second, resistance among P acnes is increasing and can occur by selective pressure during antibiotic therapy.^{3, 7, 8} Increases in P acnes resistance have been reported in all major areas of the world; many countries currently report more than 50% of P acnes strains are resistant, particularly to topical macrolides .^9-13 In acne, resistance can manifest as reduced response, no response, or relapse.^{8, 14, 15} Further, antibiotic use results in resistance among both targeted and non-targeted bacteria and resistance gene pools are often shared by pathogens and non-pathogens.^{8, 16,17-19} The likelihood of P acnes resistance increases with the patient’s age, duration of acne, and duration of treatment with topical or systemic antibiotics.⁹

Third, acne is not an infection and killing P acnes does not always “cure” acne. P acnes is a skin commensal that is present in small numbers in most post-pubertal individuals, and is found in increased numbers in the abnormal environment of increased sebum and abnormally desquamated corneocytes found in sebaceous follicles of acne patients including those without acne.^{20, 21} It is also clear that acne is not an infectious disease and simply killing P acnes may lead to an improvement but not necessarily to disease resolution.⁶

Fourth, the relative importance of antibacterial and anti-inflammatory effects of antibiotics in acne is unclear.^{22, 23} The relative contribution of these actions to antibiotic efficacy in acne remains unknown and there is some speculation that the importance of the various actions may have changed since antibiotics were first used to treat acne.^{22, 23} Antibiotics are thought to work by inhibiting inflammation; ²⁴ it should be noted that this has not been proven in vivo, but rather is suggested by large amounts of in vitro data showing that antibiotics have actions independent of bacterial killing. Topical antibiotics act quite slowly on P acnes and have a poor suppressive effect compared with benzoyl peroxide (BPO); oral antibiotics are generally considered to be more effective than topical antibiotics. ²⁴ Evidence suggests that adding BPO to a topical antibiotic improves efficacy and reduces the risk of antimicrobial resistance.^{24, 25} BPO and systemic antibiotics should be used in combination with a topical retinoid, since retinoids target acne precursor lesions (microcomedones) and have a significant effect on comedones.^*5

Topical antibiotics should never be used as monotherapy. Very sparse data support the use of topical antibiotics as monotherapy in acne.²⁶ Indeed, data from a meta-analysis of available data show a dramatic reduction in efficacy of topical erythromycin since its introduction (Figure 1). In some clinical studies,