Drug resistance and molecular epidemiological analysis of KPC-producing Escherichia coli strains isolated in Hangzhou

Abstract

Objective To analyze the epidemiological characteristics of Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli (E.coli) strains isolated in Hangzhou, China. Methods A total of 25 KPC-producing Escherichia coli strains were collected from four hospitals in Hangzhou from July 2012 to January 2014. Antibiotic susceptibility of the isolates to 22 common antimicrobial agents was determined by using Kirby-Bauer (K-B) disk diffusion method. PCR analysis and gene sequencing were used for blaKPC gene screening. The modified Hodge test was performed to detect the production of carbapenemase. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were used for homology analysis. Results All of the 25 clinical isolates were confirmed to be KPC-producing E. coli strains, harboring the blaKPC-2 gene. These KPC-producing isolates showed high drug resistance rates and were resistant to almost all β-lactam antibiotics. PFGE typing classified the 25 isolates into three main homologous clone groups, including clone group A (4 isolates), clone group B (5 isolates) and clone group C (2 isolates), and some single clones (14 isolates). MLST typing classified the isolates into eight ST types, including ST131 (14 isolates), ST167 (3 isolates), ST2003 (3 isolates), ST410 (1 isolate), ST457 (1 isolate), ST1463 (1 isolate), STnew1 (1 isolate) and STnew2 (1 isolate). The typing results of PFGE and MLST were consistent with each other. Conclusion The prevalent KPC-producing E. coli strains in Hangzhou, China were ST131 type, which were resistant to multiple antibiotics and had been detected in several hospitals. The epidemic of KPC-producing E. coli strain often occurred at some special wards, such as Intensive Care Unit (ICU) and emergency ICU. Key words: Carbapenemase; Escherichia coli; Pulsed-field gel electrophoresis; Multi-locus sequence typing