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Front. Microbiol. | doi: 10.3389/fmicb.2018.00332

The changing pattern of population structure of Staphylococcus aureus from bacteremia in China from 2013 to 2016: ST239-030-MRSA replaced by ST59-t437

 Shuguang Li1, Shijun Sun1, Chentao Yang2, Hongbin Chen1,  Yuyao Yin1,  Henan Li1, Chunjiang Zhao1 and  Hui Wang1*
  • 1Peking University People's Hospital, China
  • 2College of Medicine of Xingtai, China

To investigate the epidemiology and genetic structure of Staphylococcus aureus bacteremia in China, a total of 416 isolates from 22 teaching hospitals in 12 cities from 2013 and 2016 were characterized by antibiogram analysis, multilocus sequence typing (MLST), spa typing and staphylococcal cassette chromosome mec (SCCmec) typing. The predominant meticillin-susceptible (MSSA) genotypes in 2013 were ST188 (19.1%), ST7 (8.7%) and ST398 (7.8%), respectively, and they continued to be the main genotypes in 2016. The prevalence of meticillin-resistant S. aureus (MRSA) were 36.5% (66/181) and 36.6% (86/235) in 2013 and 2016, respectively. Interestingly, the susceptibility rates of MRSA to rifampicin and fluoroquinolones increased significantly from 2013 to 2016 (P<0.01), and this was associated with changes in genetic structure. ST239-t030-MRSA, the predominant genotype among all MRSAs in 2013 (34.8%), was replaced by ST59-t437-MRSA (15.1%) in 2016. Further analysis revealed that the ST239-t030-MRSA were more resistant to rifampicin, tetracycline and fluoroquinolones than ST59-t437-MRSA (P<0.01). To further gain insight into the mechanisms underlying the changes of genetic structure, in vitro competition and fitness measurements were performed. Importantly, ST239-t030-MRSA displayed lower growth rate and lower competitive advantage compared to ST59-t437-MRSA. Together, our findings reveal that fitness advantage of ST59-t437-MRSA over ST239-t030-MRSA may lead to changes in genetic structure and increased susceptibility of MRSA to rifampicin and fluoroquinolones in Chinese patients with S. aureus bacteremia. Our study supports temporal dynamics in MRSA clone diversities, further providing critical insights into the importance of continued monitoring of MRSA.

Keywords: MRSA, Bacteremia, population structure, Genotype, fitness cost, In vitro competition

Received: 15 Jan 2018; Accepted: 12 Feb 2018.

Edited by:

Dongsheng Zhou, Beijing Institute of Microbiology and Epidemiology, China

Reviewed by:

Fangyou Yu, Shanghai Pulmonary Hospital, Tongji University School of Medicine, China
Frieder Schaumburg, University Hospital Münster, Germany  

Copyright: © 2018 Li, Sun, Yang, Chen, Yin, Li, Zhao and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Hui Wang, Peking University People's Hospital, Beijing, China, whuibj@163.com