Solithromycin Can Specifically Induce Macrolide–Lincosamide–Streptogramin B Resistance

Objectives: Solithromycin is a fluoroketolide that is considered to be a noninducing antibiotic for macrolide–lincosamide–streptogramin B resistance mediated by erm genes. The exact activity of solithromycin to induce erm gene expression remains to be determined. Materials and Methods: The potential of solithromycin to induce erm (A), erm (C), and erm (B) gene expression was examined using a lacZ reporter assay, double-disk diffusion test, and determination of the minimal inhibitory concentration after incubation with subinhibitory concentration of different antibiotics. Results: Neither solithromycin nor the ketolides telithromycin and cethromycin induced erm (A) or erm (C) gene expression. However, solithromycin could significantly induce erm (B) gene expression at levels greater than that seen for cethromycin and clindamycin, but less than that for erythromycin, rokitamycin, and telithromycin. Conclusion: Solithromycin does not induce erm (A) and erm (C) gene expression, but does induce erm (B) gene expression, although to a weaker extent than that seen for macrolides.