In vitro antibacterial activity of telithromycin against Enterococcus spp. isolated from China

Abstract

Background: Enterococci has resistant to a wide range of antimicrobials, and the treatment of enterococcal infection has always been an issue of concern. This study aimed to explore the new ketolides antimicrobials-telithromycin, against the planktonic cells and biofilms of enterococci. The minimum inhibitory concentration (MIC) of telithromycin was determined. The sequence types (STs) and genotypes of resistance to erythromycin in enterococci were detected. Furthermore, the effect of telithromycin against the biofilms of enterococci were investigated.Results: A total of 280 Enterococcus faecalis and 122 Enterococcus faecium isolates were collected from individual inpatients in China. Telithromycin showed excellent activity against the E. faecalis and E. faecium strains no matter sensitive or resistant to erythromycin with erm A, erm B or erm C, with the MIC50 at 2 μg/mL and 4 μg/mL, respectively. The predominant STs of E. faecalis isolates were ST16, ST30, ST179, and ST18, ST78, ST80 were the predominant STs of E. faecium isolates. Moreover, 87.1% (135/158) and 80.4% (41/51) isolates of the predominant STs carried the erm genes in E. faecalis and E. faecium isolates, respectively. The subinhibitory concentration of telithromycin (at 1/4× and 1/8× MICs) significantly inhibited the biofilm formation of 16 E. faecalis isolates. Telithromycin (at 8× MIC) indicated the removal effect on the established biofilms of 8 E. faecalis isolates, and combined with ampicillin eradicated more biofilms than telithromycin or ampicillin alone.Conclusion: Telithromycin showed an excellent activity against the planktonic cells of E. faecalis and E. faecium, and against the biofilms of E. faecalis.