Genotype and Drug Resistance of Klebsiella Pneumoniae from Hubei Expressing CTX-M Extended Spectrum Beta-lactamase

Objective To explore the transmission mechanisms of Klebsiella pneumoniae from Hubei expressing CTX-M β-lactamases,providing bases for rational use of antibiotics in clinic. Methods A total of nonrepetitive 70 K.pneunoniae producing ESBLs were detected by phenotypic confirmatory test based on NCCLS criteria.PCR-RFLP and DNA sequencing were carried out for blaCTX-M typing;Susceptibility of the CTX-M producing strains to 9 antibiotics was performed through a disk diffusion test;DNA homology of clonal strains was analyzed by plasmid transfer experiments and RAPD. Results The incidence of CTX-M expression was 46% in ESBLs-producing isolates,all of which was CTX-M-1 subtype,and CTX-M-3 was the most common type.The strains with CTX-M were resistant to a lot of antibiotics,but 100% sensitive to imipenem.The resistance mediated with ESBLs in CTX-M strains was horizonly transferred.The strains were from different clones by DNA homological analysis. Conclusion Imipenem could be the drug of first choice for treating K.pneumoniae with CTX-M β-lactamases-producing strains.The transmission of CTX-M producing strains is mainly mediated by plasmids,which forces us to intensify the detection of ESBLs strains with CTX-M type in Hubei province.