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Original Research

Microbiological Characteristics of Carbapenem-Resistant Enterobacteriaceae Clinical Isolates Collected from County Hospitals

, , , , , & show all
Pages 1163-1169 | Published online: 22 Apr 2020
 

Abstract

Objective

To investigate the molecular characteristics of carbapenem-resistant Enterobacteriaceae (CRE) from county hospitals in China.

Materials and Methods

Forty-three sequential non-duplicate CRE strains (including 33 Klebsiella pneumoniae isolates, 4 Enterobacter cloacae isolates, 3 Escherichia coli isolates, 1 Serratia marcescens, 1 Morganella morganii and 1 Citrobacter freundii) were collected from 4 county hospitals and 2 municipal hospitals. Antimicrobial susceptibility testing was conducted by broth microdilution method, using 3-aminophenylboronic acid and EDTA and the modified carbapenem inactivation method (mCIM) to screen phenotype of carbapenemase. β-Lactamases were characterized by polymerase chain reaction (PCR) and DNA sequencing. The transferability of blaNDM-5 was investigated by transformation experiment. Clonal relatedness was evaluated by pulsed-field gel electrophoresis and multilocus sequence typing .

Results

The results of antimicrobial susceptibility testing indicated that 43 CRE strains were resistant to most of the antimicrobial agents, except tigecycline and colistin. Overall, 93%, 93%, and 97.7% of these strains were resistant to imipenem, meropenem, and ertapenem, respectively. PCR and DNA sequencing indicated that 67.4% (29/43) were blaKPC-2 positive isolates, in which 3.4% (1/29) was coproduced with blaNDM-1. In addition, 7.0% (3/43), 4.7% (2/43), 4.7% (2/43), 2.3% (1/43), 2.3% (1/43) were blaNDM-1, blaNDM-16, blaNDM-4, blaNDM-5, blaIMP-4 positive isolates, respectively. The 29 blaKPC-2-positive isolates belonged to 12 different PFGE type and designated as ST11 (n=20) and ST15, ST39, ST116, ST667, ST2245, ST2338. The plasmid bearing blaNDM-5 could be transferred into recipient E. coli J53 through transformation.

Conclusion

Our study indicated the dissemination of CRE between the tertiary hospitals and secondary hospitals.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (grant no. 81871690, 81902101), self-financing program of science and technology plan project of Lishui city, Zhejiang province (2016ZCGYX15), Chinese Hospital Infection Fund (ZHYY2015-0015) and CHINET Antimicrobial Surveillance Network (grant WI207259). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

Disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.