A study on the MIC of antibiotics for Propionibacterium acnes in patients with acne

Abstract

Background. Propionibacterium acnes plays an important role in the development of inflammatory acne, and inflammatory lesions are improved by oral and topical antibiotics. But as P. acnes frequently develop resistance to antibiotics in patients receiving long-term systemic antibiotic therapy, the therapeutic effects diminish, and eventually therapy fails. Objective. The purpose of this study is to evaluate the general susceptibility of P. acnes to antibiotics and the difference in the MIC depending on the use of oral and/or topical antibiotics, therapeutic effects and disease duration in patients with acne vulgaris. Methods. We used twenty-six strains of P. acnes which were obtained from patients with acne and performed susceptibility testing for antibiotics using the E test procedure. Results. 1. The growth of P. acnes was completely inhibited by erythromycin and chloramphenicol at concentrations of 0.023 μg/ml and 0.064 μg/ml, respectively, by cefoxitin at 0.094 μg/ml, and by tetracycline and clindamycin at 0.190 μg/ml. 2. P. acnes was most susceptible to erythromycin, and followed by chloramphenicol, cefoxitin, tetracycline, clindamycin in order of decreasing susceptibility. 3. There were no significant differences in the MIC in relation to previous antibiotic treatment. 4. For tetracycline, the MIC was significantly lower (p < 0.01) in patients who improved after treatment. 5. For tetracycline and chloramphenicol, the MIC was significantly lower (p < 0.05) in patients with less than 2 years disease duration. Conclusion: The susceptibility of antibiotics for P. acnes was highest in erythromycin. There were no significant differences in the MIC in relation to previous antibiotic treatment, and for some antibiotics the susceptibility was low in patients who did not show clinical improvement or who had long disease duration.