Prevalence of extended-spectrum beta-lactamases-producing Escherichia coli and Klebsiella pneumoniae in community-onset bloodstream infections from county hospitals of Zhejiang Province

Abstract

Objective To study the epidemiology and genotypes of extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli (EC) and Klebsiella pneumoniae (KP) that caused community-onset bloodstream infections (COBSI) in 9 county hospitals of Zhejiang Province. Methods This is a multi-center, prospective, observational study. The cases and isolates with COBSI caused by EC and KP were consecutively collected from 9 county hospitals in Zhejiang Province between 1st March 2014 and 30th April 2015. The double disk diffusion method was used to confirm the production of ESBL. The ESBL genotypes were determined by polymerase chain reaction(PCR) amplification and sequence analysis. Multi-locus Sequence Typing (MLST) was used to analyze the homology of ESBL-producing isolates. Minimal inhibitory concentration (MIC) of frequently used drugs for ESBL-producing isolates was determined by in-vitro antimicrobial susceptibility tests. Results During the study period, a total of 172 cases with COBSI were collected and 171 cases were eligible, among which 126 were caused by EC and 45 were caused by KP. The overall prevalence of ESBL was 34.5% (59/171), and the prevalence of ESBL-EC and -KP was 41.3% (52/126) and 15.6% (7/45), respectively. CTX-M-type ESBL accounted for 96.6% (57/59) of all the ESBLs-producing isolates, and the most common type was CTX-M-14 (27.1%, 16/59), followed by CTX-M-55 (22%, 13/59). MLST analyses revealed significant genetic diversity among ESBL-EC and -KP. The most prevalent ST of ESBL-EC was ST131 (23.1%). In addition to carbapenems, cefoperazone/sulbactam, piperacillin/tazobactam, moxalactam, amikacin and fosfomycin also showed good in-vitro activity against ESBL-EC and -KP. Conclusions The prevalence of ESBL in EC and KP is high in 9 county hospitals of Zhejiang Province, and the most common genotypes are CTX-M-14 and CTX-M-55. The detection rate of ESBL in EC is higher than in KP. It could be considered adequate empirical therapy according to the results of antimicrobial susceptibility tests. Carbapenems, cefoperazone/sulbactam, piperacillin/tazobactam, moxalactam, amikacin and fosfomycin have good in-vitro activity against ESBL-EC and -KP. Key words: Extended-spectrum beta-lactamases; Community-onset; Bloodstream infections; Escherichia coli; Klebsiella pneumoniae