Prevalence Of Extended-spectrum Beta-Lactamases-Producing Escherichia Coli And Klebsiella Pneumoniae In Community-Onset Bloodstream Infections From County Hospitals Of Zhejiang Province

Objective:To study the epidemiology and genotypes of extended-spectrum beta-lactamases(ESBLs)-producing Escherichia coli(EC)and Klebsiella pneumoniae(KP)that caused community-onset bloodstream infections(COBSIs)in 9 county hospitals of Zhejiang Province.Methods:The cases and isolates with COBSIs caused by EC and KP were 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 ESBLs.The ESBLs genotypes were determined by PCR amplification and sequence analysis.Multilocus Sequence Typing(MLST)was used to analyze the homology of ESBLs-producing isolates.Antimicrobial susceptibility tests(ASTs)were performed using standard microbroth dilution method,agar dilution method and E-test method according to the CLSI.Results:During the study period,a total of 171 cases with COBSIs were collected,among which 126 were caused by EC and 45 were caused by KP.The overall prevalence of ESBLs was 34.5%(59/171),and the prevalence of ESBLs-EC and-KPwas 41.3%(52/126)and 15.6%(7/45),respectively.CTX-M-type ESBLs accounted for 96.6%(57/59)of all the ESBLs-producing isolates,and the most common was CTX-M-14(27.1%,16/59),followed by CTX-M-55(22%,13/59).MLST analyses revealed significant genetic diversity among ESBLs-EC and-KP.The most prevalent ST of ESBLs-EC was ST131(23.1%).In addition to carbapenems,?-lactamase/?-lactamase inhibitor combinations,moxalactam,amikacin and fosfomycin also showed good in-vitro activity against ESBLs-EC and-KP.Conclusion:The prevalence of ESBLs in EC was significantly higher than KP in 9 county hospitals of Zhejiang Province.The most common genotypes were CTX-M-14 and CTX-M-55.Clinicians could consider adequate empirical therapy according to the results of ASTs.