The expression of ESBLs genes in Escherichia coli isolates induced by β-lactam antibiotics and inhibited by histidine kinase inhibitors / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the genotypes of extended spectrum β-lactamases (ESBLs) and their carrying modes in Escherichia coli (E.coli) isolates,and to analyze the mechanism of protein phosphorylation and ESBLs gene expression induced by β-lactam antibiotics or inhibited by histidine kinase inhibitors.Methods The predominant genotypes of ESBLs (KPC,TEM,SHV and CTX-M) and their carrying modes were identified by PCR and sequencing analysis.E-test and micro-tube dilution method were applied to measure minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs).Immobilized metal ion affinity chromatography,bacterial protein phosphorylation detection kit and real-time fluorescent quantitation RT-PCR were performed to analyze the enhancing effects of 1/4 MIC penicillin or cefotaxime or the inhibitory effects of histidine kinase inhibitors (closantel,bromized or iodized methylimidazol) on protein phosphorylation and the expression of ESBLs at mRNA level in E.coli isolates.Results In 183 β-lactam antibiotics-resistant E.coli isolates,TEM and CTX-M genes (83.1％ and 77.1％) were highly expressed than other two ESBLs genes with a prevalent carrying mode of coexisting (65.0％) (P＜0.05).Penicillin or cefotaxime at 1/4 MIC induced the protein phosphorylation and promoted the expression of TEM,SHV and CTX-M at mRNA level (P＜0.05).Closantel (200 μmol),bromized methylimidazol (2 or 10 μmol) or iodized methylimidazol (20 or 50 μmol) could neither kill E.coli isolates nor inhibit their growth,but could inhibit the protein phosphorylation induced by above mentioned antibiotics and enhance the expression of ESBLs at mRNA level (P＜0.05).Moreover,the susceptibility of antibioticresistant E.coli strains to penicillin and cefotaxime were increased (P＜0.05).Conclusion TEM and CTX-M were the predominant genotypes of ESBLs carried by β-lactam antibiotics-resistant E.coli strains isolated from Zhejiang province,which were mostly found in a TEM plus CTX-M carrying mode.Sublethal dose of β-lactam antibiotics could up-regulate the expression of ESBLs genes in E.coli isolates via TCSS,but it could be inhibited by histidine kinase inhibitors.