Antibiotics Use in Acne Unintentionally Lower S. aureus Colonization

22 Jan Antibiotics Use in Acne Unintentionally Lower S. aureus Colonization

Posted at 00:57h in Author Interviews, Dermatology, Infections by Marie Benz MD FAAD

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MedicalResearch.com Interview with:
Gregory R. Delost, DO
University Hospitals Regional Hospitals
Richmond Heights, OH

MedicalResearch.com: What is the background for this study?

Dr. Delost: Acne vulgaris is a common dermatological disorder with an incidence of approximately 85% in adolescents and young adults. Treatment options include topical antibiotics, topical retinoids, benzoyl peroxide, oral antibiotics and isotretinoin. Antibiotics are generally prescribed for cases of moderate to severe acne. However, long-term antibiotic use may affect the normal flora bacteria and perhaps promote the development of antibiotic resistant bacteria. There is little prospective research in outpatient settings to determine if these concerns are valid. In our study, we used a prospective, cross-sectional, quasi-experimental design, which compared colonization of Staphylococcus aureus in 263 patients undergoing treatment for clinically diagnosed acne in two northeastern Ohio dermatology practices.

MedicalResearch.com: What are the main findings?

Dr. Delost: Prolonged use of antibiotics (both oral and topical) in acne patients significantly lowered the prevalence of S. aureus colonization. In our isolates, the most common antibiotics that we found bacterial resistance to were erythromycin and clindamycin, regardless of the control or experimental group. Treatment of acne patients with antibiotics did not significantly alter the resistance rates; however we found resistance to one or more of the antibiotics tested was more commonly observed in acne patients who were treated with antibiotics.

Twenty-eight (10.6%) of the participants were colonized with S. aureus. Those who were using antibiotics were less likely to be colonized by S. aureus (6.3%) than those who were not using antibiotics (15.7%). Six of the nine (66.7%) of the S. aureus isolates from the subjects taking antibiotics were resistant to one or more of the antibiotics tested, while those participants who were not using oral or topical antibiotics had nine of the nineteen (47.4%) isolates that were resistant to one or more antibiotics tested. Those participants who were not taking antibiotics had a 5.3% methicillin resistant Staphylococcus aureus (MRSA) carriage rate while those taking antibiotics had an MRSA carriage rate that was over double (11.1%) that of the control group.

Interestingly, there were six patients in our study who were treated with isotretinoin; four of the six (66.7%) were colonized with S. aureus. Furthermore, there was no antibiotic resistance in any of these isolates.

Antibiotic use, age, gender, and duration of antibiotic therapy were assessed as predictor variables using colonization by S. aureus as the outcome variable with logistic regression analysis. Antibiotic use was the only significant predictor (Exponential beta = 2.850), indicating that those participants taking antibiotics were 2.85 times more likely not to carry S. aureus.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Delost: Antibiotic prescribing practices for acne patients may have the positive unintended consequence of lowering S. aureus colonization. This may be explained by the observation that the antibiotics that dermatologists commonly use to treat acne are still effective against treating S. aureus and MRSA. While dermatologists may be inadvertently lowering S. aureus rates in acne patients who are using antibiotics, it is important to limit antibiotic use to appropriate clinical situations to reduce multi-drugs antibiotic resistance in the unlucky subset of patients who carry S. aureus after taking antibiotics for acne. Additionally, clinicians should be cognizant on limiting the duration of antibiotic therapy. Benzoyl peroxide, which does not promote antibiotic resistance, provides a viable adjuvant therapy to combine with antibiotics. Still, the use of topical retinoids and isotretinoin in acne patients who can tolerate this treatment provide a therapeutic alternative to antibiotics. The rise of erythromycin and clindamycin resistance should be a caveat since these two antibiotics are mainstay components in topical acne treatment regimes.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Delost: This study was somewhat limited by its cross-sectional design. Thus, the use of a longitudinal study which tracks S. aureus carriage in acne patients from initial evaluation and following each treatment point would provide a clearer picture of the carriage of S. aureus and any antibiotic resistance. We would culture the throat in addition to the anterior nares to better assess the carrier state. Additionally, it would be interesting to see if S. aureus carriage rate and antibiotics resistance correlated with more severe acne or cases that are recalcitrant to treatments.

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