Phenotypic and molecular characterization of resistance to macrolides and Lincosamides in Corynebacterium striatum clinical strains isolated from Tunisia

Abstract

Objectives: In this study we investigated the susceptibility profiles against macrolides and lincosamides of 85 C. striatum strains isolated at a clinical centre in Sousse (Tunisia). Methods: The strains were identified by the routine biochemical assays and then confirmed by Vitek-Maldi-Tof-MS. MIC?s of erythromycin and clindamycin were determined using the microdilution method. The detection of erm(X), erm(B), msr(A), mph(A) and mef(A-E) resistance genes was performed by PCR. The strains were typed by PFGE using XbaI. Results: Sixty-nine (81.17%) strains were resistant to erythromycin, 58 (67.44%) strains were resistant to clindamycin. There was a high correlation between the resistance to erythromycin and clindamycin and the presence of erm(X) gene in 85.50% and 89.65% respectively. The erm(B) gene was detected in 21(24.70%) strains whereas, no others genes were detected in our strains collection. By PFGE, the 85 strains belonged to 18 different clones. Conclusion: erm(X) is implicated in macrolide resistance for almost all the Corynebacterium strains analyzed in our study. Other resistance genes like erm(B) must also be implicated in this resistance, although its presence seems to be unusual in previously reported studies.