Erythromycin-resistance of cutaneous bacterial flora in acne

Some studies have raised the problem of an increase of bacterial resistance in acne patients. This study was carried out in France, where no previous studies about resistance to erythromycin has been performed, on 40 patients with mild to moderately severe acne. Microbiological samples were obtained by using Williamson and Kligman metho d. This study showed that the prevalence of bacterial resistance to erythro mycin was 95% for Staphylococcus epidermidis strains and 52% for Propioniba cterium acnes strains. Resistant strains were more frequent in patients with predominantly inflamm atory lesions (papules and pustules). The influence of previous or current treatment with erythromycin was also studied and showed that even patients without any previous use of erythromycin had resistant strains for Propioni bacterium acnes (42%). In addition the minimum inhibitory concentrations (M IC) for zinc were evaluated. All the Propionibacterium acnes strains tested were inhibited at concentrations less or equal to 512 mug/ml of zinc. Howe ver, zinc combined with erythromycin in vitro did not modify the erythromyc in MIC. This first French study on bacterial resistance to erythromycin in acne pat ients confirms the results of studies performed in other countries.