Nationwide Surveillance of Clinical Carbapenem-resistant Enterobacteriaceae (CRE) Strains in China

Rong Zhang,Lizhang Liu,Hongwei Zhou,Edward Waichi Chan,Jiaping Li,Ying Fang,Yi Li,Kang Liao,Sheng Chen

doi:10.1016/j.ebiom.2017.04.032

Abstract

The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE) - mediated hospital infections in China prompted a need to investigate the genetic basis of emergence of such strains. A nationwide survey was conducted in China covering a total of 1105 CRE strains collected from 25 geographical locales with results showing that acquisition of two carbapenemase genes, blaKPC-2 and blaNDM, was responsible for phenotypic resistance in 90% of the CRE strains tested (58% and 32% respectively), among which several major strain types, such as ST11 of K. pneumoniae and ST131/ST167 of E. coli, were identified, suggesting that dissemination of specific resistant clones is mainly responsible for emergence of new CRE strains. Prevalence of the fosA3 gene which mediates fosfomycin resistance, was high, while the colistin resistance determinant mcr-1 was rarely present in these isolates. Consistently, the majority of the blaNDM-bearing plasmids recoverable from the test strains belonged to IncX3, which contained a common core structure, blaNDM-blaMBL-trpF. Likewise, the core structure of ISKpn27-blaKPC-2-ISKpn2 was observed among plasmids harboring the blaKPC-2 gene, although they were genetically more divergent. In conclusion, the increasing prevalence of CRE strains in China is attributed to dissemination of conservative mobile elements carrying blaNDM or blaKPC-2 on conjugative and non-conjugative plasmids.

Highlights

The scale of clinical and public health problems due to multidrugresistant bacterial infections has further escalated in recent years following the emergence of blaNDM, a plasmid-borne carbapenem resistance gene that has been widely disseminated among various species of bacterial pathogens worldwide (Kumarasamy et al, 2010; Nordmann et al, 2012)
The minimal inhibitory concentrations (MICs) of 12 antibiotics, namely amoxicillin-clavulanic acid, cefotaxime, ceftazidime, imipenem, mropenem, amikacin, ciprofloxacin, colistin, fosfomycin and tigecycline, were determined using the agar dilution method, and the results were analyzed according to the CLSI criteria of 2016 (Huang et al, 2016; CLSI, 2016)
Findings of this work confirmed that production of carbapenemases is the major mechanism of carbapenem resistance in carbapenem-resistant Enterobacteriaceae (CRE) in China, among which NDM and KPC-2 were the major carbapenemases concerned

Summary

Introduction

The scale of clinical and public health problems due to multidrugresistant bacterial infections has further escalated in recent years following the emergence of blaNDM, a plasmid-borne carbapenem resistance gene that has been widely disseminated among various species of bacterial pathogens worldwide (Kumarasamy et al, 2010; Nordmann et al, 2012). Descriptions such as “superbug”, “nightmare bacteria” and “post-antibiotic era” reflected the seriousness of the antimicrobial resistance issue. Approximately 600 deaths result from infections caused by the two most common types of CRE, namely carbapenem-resistant Klebsiella spp. and E. coli (Yong et al, 2009)

Methods

Results

Conclusion