Predominance of ST5-II-t311 clone among healthcare-associated methicillin-resistant Staphylococcus aureus isolates recovered from Zhejiang, China

Objectives: To determine the molecular characteristics and antimicrobial susceptibility of healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) in Zhejiang Province. Methods: A total of 391 HA-MRSA isolates were collected from 12 hospitals in five cities of Zhejiang Province, between January 2012 and May 2013. Susceptibility to vancomycin, teicoplanin, linezolid, tigecycline, and daptomycin was determined. Resistant isolates were screened for resistance mutations. Ten isolates from each hospital were then chosen at random for molecular typing. Results: The isolates showed good susceptibility to all five anti-MRSA agents; only five sporadic nonsusceptible isolates were detected. CC5/ST5-MRSA-II-t311 (39/120, 32.5%) was found to be the predominant HA-MRSA clone and was spread between the different hospitals in Hangzhou. CC5/ST5-MRSA-II-t002 was the most prevalent clone in Ningbo, while CC239/ST239-MRSA was epidemic only in certain hospitals in Wenzhou and Shaoxing. Fifteen ST59 isolates (15/120,12.5%) were identified among the HA-MRSA isolates. Conclusions: CC5/ST5-MRSA-II-t311 has become the predominant HA-MRSA clone in Hangzhou, Zhejiang Province. ST59 MRSA has spread into hospitals. The isolates showed good susceptibility to all five anti-MRSA agents. (C) 2018 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.