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Predominant β-lactamase genotypes of Escherichia coli isolates and induction and inhibition mechanisms of β-lactamase gene expression / 中华流行病学杂志
Chinese Journal of Epidemiology ; (12): 484-490, 2015.
Artigo em Chinês | WPRIM | ID: wpr-240067
ABSTRACT
Objective To understand the predominant β-lactamase genotypes and their carrying modes ofEscherichia coli isolates in Zhejiang province,and the effects of β-1actam antibiotics on inducing or histidine kinase inhibitor closantel (CLO) on inhibiting the expression of β-1actamase genes.Methods Micro-dilution method and E-test were applied to measure the resistant rate and minimal inhibitory concentration (MIC) in E.coli isolates against β-1actam antibiotics.PCR and sequence analysis of PCR products were conducted to detect the β-lactamase genotypes and their carrying modes.Real-time fluorescent quantitative RT-PCR and β-lactamase confirmation test were performed to determine the influence of 1/4 MIC penicillin and cefotaxime,and CLO on the transcription and expression of β-lactamase genes in the resistant E.coli isolates.Results Among the 462 E.coli strains isolated in Zhejiang,285 (61.7%) were resistant to penicillin,ampicillin,cefoxitin,cefotaxim and ceftazidime.In the 285 resistant isolates,the detection rate of TEM or CTX-M β-1actamase gene (83.2% or 75.1%) was significantly higher than that of KPC,SHV or OXA β-lactamase gene (1.4%-10.2%) (P<0.01) and the carrying rate of two or more β-1actamase genes (68.8%) was also significantly higher than that of single β-1actamase gene (31.2%) (P<0.01),and 61.4% of the resistant isolates carried TEM + CTX-M genes (P<0.01).Except KPC gene,1/4 MIC of cefotaxim and penicillin induced a rapid increase of TEM-mRNA,CTX-M-mRNA,SHV-mRNA or OXA-mRNA levels (P<0.01),but 50-500 μg/ml CLO inhibited these levels (P<0.01).After pre-treatment with 100 μg/ml CLO,82.8%-85.6% of the resistant isolates became sensitive to β-lactam antibiotics (P<0.01),while the detection rate of β-lactamases was also decreased from 95.1% to 16.1% (P<0.01).Conclusion TEM and CTX-M are the predominant β-lactamase genotypes in E.coli isolates in Zhejiang and TEM+CTX-M is the predominant carrying mode of β-lactamase genes.Low concentrations of β-lactam antibiotics can up-regulate the expression levels of β-lactamase genes in E.coli through bacterial two-component signaling systems,but this effect can be inhibited by CLO,a histidine kinase inhibitor.

Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Idioma: Chinês Revista: Chinese Journal of Epidemiology Ano de publicação: 2015 Tipo de documento: Artigo

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Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Idioma: Chinês Revista: Chinese Journal of Epidemiology Ano de publicação: 2015 Tipo de documento: Artigo