Study On Cephalosporin Resistance And ESBLs Genotyope In Escherichia Coli And Klebsiella Pneumoniae

Objective To investigate genotype and drug resistance of ESBLs producing Escherichia coli and Klebsiella pneumoniae isolated from weihai municiple hospital.Method Clinical isolates of ESBL producing Escherichia coli(n=40) and Klebsiella pneumoniae strains(n=20) were collected according to the Screening and Confirmatory Tests for ESBLs recommended by the CISI. Plasmid DNA was extracted by alkaline lysis method. PCR analysis was used to amplify TEM, SHV-1, CTX-M genes, respectively. Gene sequence alignment was performed in Genbank to identify the β-lactamase genotype. Agar dilution test was used to detected MIC value for the strains which only produce only one genotype ESBL.Results Genes of blaTEM-1,, blasHV-1, blaCTX-M-3and blaCTX-M-9group were detected in60strains except blaCTX-M-2group. Sequence analysis of ESBLs gene showed that a total of7genotypes of ESBLs were identified.100%E.coli and80%K.pneumoniae expressed blaCTX-M.25%K.pneumoniae were confirmed expressing blasHV-12.The most prevalent CTX-M genes in E.coli and K.pneumoniae were CTX-M-14(45.0%and35.0%), followed by CTX-M-55(35.0%) and CTX-M-15(20.0%and15%). CTX-M-3, CTX-M-65, CTX-M-123and CTX-M-101account for fewer percentage of CTX-M genotype.12.5%(5/40) E.coli and25%(5/20) K.pneumoniae carried2types of CTX-M genes. Ceftazidime hydrolyzing blaCTX-M-15,CTX-M-55,CTX-M-101account for62.5percent for E.coli and55percent for K.pn.(2) All ESBLs-producing strains were resisitant to cefotaxime. Except for a strain of K.pn showed intermediate to imipenem, others showed susceptible to imipenem and meropenem. The resistance rate to ceftazidime of ESBLs producing E.coli and K.pneumoniae was30%and65%, respectively. Ciprofloxacin and Levofloxacin shared the same resistance against E.coli and K.pn. the resistance rate were62.5%and70%, respectively.(3)D240G substitution were found in the molecular of CTX-M-15, CTX-M-55, CTX-M-101and CTX-M-123enzyme which were not susceptible to ceftazidime while strain producing blaCTX-14,65which were not occurred D240G substitution were susceptible. It was significant different between the two group gene (Fisher’s exact test (bilateral) P=1.41*10-4).Conclusions The most prevalent ESBLs genotype were CTX-M-14and CTX-M-55, CTX-M-101and CTX-M-123genotype are the first time detected in Shangdong. Producing blaCTX-M-15, CTX-M-55, CTX-m-101is an important Mechanism of resistance for E.coli and K.pn. The two kind of strains were severely resistant to ciprofloxacin and levofloxacin. Carbapenems are the drug of choice for infection caused by such bacteria. The resistant characteristic of strains isolated in our hospital was in accordance with current CLSI2010CTX breakpoint, but were not accordance with CAZ and FEP breakpoints.