ABSTRACT
Objective To investigate the spreading characteristics of plasmid-mediated resistance and the clones dissemination in multidrug resistant Klebsiella pneumoniae.Methods A total of 53 strains of multidrug resistant Klebsiella pneumoniae were successively collected from the First Affiliated Hospital,Zhejiang University School of Medicine during December 2009 and February 2012.Antimicrobial agents susceptibility was determined by Kirby-Bauer (K-B) method,and pulsed field gel electrophoresis (PFGE) was used to investigate the clonality of clinical isolates.Filter mating method was used for plasmid conjugation,and the relative molecular mass of the plasmid was determined using S1-PFGE assay.PCR amplification and sequencing were used to screen common antimicrobial resistance genes.Results Fiftythree clinical isolated Klebsiella pneumoniae strains were all resistant to penicillins,and their sensitive rates to piperacillin/tazobactam,cefoperazone/sulbactam were below 15％.More than 86％ strains were resistant to cephalosporins,and 60％-70％ strains were resistant to quinolones,sulfonamides and tetracyclines.About 50％ strains were resistant or intermediate sensitive to carbapenems.PFGE results did not support the evidence of clone dissemination.Resistant isolates harbored conjugant plasmid with 34 000-355 000 bp size,which encoded penicillins,cephalosporins,carbapenems or aminoglycoside resistant determinants,including CTX-M,TEM,KPC type β-1actamase genes and plasmid-mediated quinolone resistance gene qnr.Conclusions Multidrug resistance is prevalent in clinical Klebsiella pneumoniae isolates.Rapid prevalence of resistance is mainly determined by conjugant plasmid horizontal transfer rather than simple clone dissemination.