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

Abstract

Shujin Xie,1,2,* Shiming Fu,3,* Mengwei Li,4 Zhusheng Guo,2 Xuehai Zhu,2 Jianmin Ren,5 Fupin Hu1,6 1Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China; 2Tungwah Hospital of Sun Yat-Sen University, Dongguan, People’s Republic of China; 3Department of Clinical Laboratory, The Traditional Chinese Medical Hospital of Suichang, Zhejiang, People’s Republic of China; 4Clinical Microbiology Laboratory, Department of Liuzhou Worker Hospital, Guangxi, People’s Republic of China; 5Institute of Antibiotics, The Central Hospital of Lishui City, Zhejiang, People’s Republic of China; 6Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fupin HuInstitute of Antibiotics, Huashan Hospital, Fudan University, 12 M. Wulumuqi Road, Shanghai 200040, People’s Republic of ChinaTel [phone]Fax [phone]Email [email protected]: 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.Keywords: Enterobacteriaceae, blaKPC-2, blaNDM-1

Keywords

• enterobacteriaceae
• blakpc-2
• blandm-1