Antibacterial Susceptibility Testing of Cutibacterium acnes in Acne Vulgaris Patients

INTRODUCTION: Combination therapy is widely used for the treatment of acne vulgaris (AV), including local anti-inflammatory drugs containing antimicrobials, such as clindamycin or erythromycin, to inhibit Cutibacterium acnes (C. acnes) growth and at the same time reduce the production of inflammatory mediators. The aim of the study is to compare the antibacterial susceptibility of C. acnes to clindamycin and erythromycin in AV patients compared with healthy patients in the control group (CG). METHODS: The prospective study included 56 patients with clinically diagnosed AV symptoms and 12 patients were included in the CG who did not have AV. In the AV group, patient specimen was contents of pustules obtained by squeezing pustules, but in the CG, the specimen was content of sebaceous glands. All specimens were cultivated on a combined Mueller–Hinton solid medium. Identification was done by VITEK2 and followed by determination of antibacterial susceptibility of the isolated C. acnes strains by E-test. RESULTS: C. acnes was isolated from samples of 28 (50%) in the AV group, whereas in the CG, C. acnes was isolated from 10 samples (80%). Resistance to clindamycin in both groups was similar, in 6 (21.4%) samples from patients in the AV group and in 2 (20.0%) samples in the CG, but resistance to erythromycin in the AV patients was higher compared to the CG, in 8 (28.6%) and 1 (10%) accordingly. CONCLUSION: Patients with AV have higher rates of resistance to erythromycin than the CG, while resistance to clindamycin is comparable. Resistance data showed no statistically significant association between use of erythromycin and clindamycin and the development of resistance. More C. acnes were identified in the CG than in the AV group.