Effect of antibiotics on the oropharyngeal flora in patients with acne

Objective: To estimate the prevalence and resistance patterns of Streptococcus pyogenes and Staphylococcus aureus in the oropharynx of individuals with acne who were using or not using antibiotic therapy. Design: A cross-sectional study. Setting: The Dermatology Department of the Hospital of the University of Pennsylvania, Philadelphia. Patients: Patients with acne. Main Outcome Measures: Presence or absence of S pyogenes and S aureus in the oropharynx as determined by culture and their resistance patterns to tetracycline antibiotics as determined by agar disk diffusion. Results: Of 105 patients who participated, 42 were using oral or topical antibiotics and 63 patients were not using antibiotics. Six (10%) of those 63 not using any antibiotics had positive S pyogenes cultures compared with 13 (33%) of those successfully evaluated using antibiotics (n=39) (prevalence risk ratio, 3.5; 95% confidence interval, 1.4-8.6; P=.003). A total of 85% of S pyogenes cultures (11/13) from those using antibiotics were resistant to at least I tetracycline antibiotic compared with 20% (1/5) from those not using antibiotics (P=.01). Of those not using antibiotics, 29% (18/62) had positive S aureus cultures compared with 22% (9/41) of those using antibiotics (prevalence risk ratio, 0.76; 95% confidence interval, 0.38-1.5; P=.42). No significant differences in resistance patterns of S aureus were found. Conclusions: Streptococcus pyogenes colonization and resistance in the oropharynx are associated with antibiotic therapy in patients with acne. The clinical and longterm effects of this finding need to be studied further.