Study On Inhibitor-resistant β-lactamases Among Escherichia Coli

Objective We studied on inhibitor-resistant β -lactamases (IRBL) among Escherichia coli (E. coli) in China, so as to find whether IRBL exists in China and what the type of IRBL, which the bacteria produces IRBL.Methods We collected clinical strains of Escherichia coli from May 15, 2005 to December 1, 2005 in West China hospital of Sichuan University. A total of 727 E. coli strains enrolled in. The minimum inhibitory concentration (MIC) of amoxicillin-clavulanic acid, piperacillin, piperacillin-tazobatam, cefozolin, cephalothin and cefoxitin against E. coli were assayed by agar dilution method based on CLSI standards. After the primary screening, 52 strains are resistant to amoxicillin/clavulanic acid and sensitive to cefazolin according to CLSI criteria. We use PCR to amplify the gene of inhibitor-resistant TEM (IRT) of these 52 strains. DNA sequence is performed for PCR products. The sequencing results were compared with other IRBL genes in Genbank by using BLAST for similarity. And the proteins coded by PCR products were also compared with other IRBL proteins in Genbank by using BLAST.Results The whole IRT genes of 23 E. coli strains were positively amplified by PCR. The 18 IRT DNA sequences is the same as that of coding sequence of TEM-1. The IRT coding sequences of 3 strains of E. coli are equal to each other but different from...