Characterization of Teicoplanin Nonsusceptible Staphylococcus epidermidis Clinical Isolates Belonging Predominantly to ST267.

Staphylococcus epidermidis is the main cause of bacteremia and infections of indwelling catheters, glycopeptide antibiotics are often considered as the choice of empirical drugs for the treatment of staphylococcal infections. In the present study, 12 teicoplanin nonsusceptible S. epidermidis isolates were collected between January and October 2013. All strains carried the mecA gene, displayed multiple drug resistance, and showed heterogeneous resistance to vancomycin using the population analysis profiling/area under the curve method. Multilocus sequence typing revealed four different sequence types among these isolates; eight isolates belonged to the same ST type (ST267). Pulsed-field gel electrophoresis (PFGE) with SmaI endonuclease showed four distinct pulsotypes. Six isolates that belonged to ST267 shared the same PFGE bands, indicating that they were clonally related. In addition, cell wall thickening and decreased autolysis were found in these isolates. Our study demonstrated that ST267 was the most epidemic clone among teicoplanin nonsusceptible S. epidermidis and identified a potential endemic clone in this region, which was believed to be the first report that the ST267 clone has spread in China. Our findings revealed that strengthened monitoring of S. epidermidis for drug resistance to glycopeptide antibiotics is urgently needed, and heightened measures should be taken to control the further spread of the ST267 clone.