Imipenem resistance in clinical Escherichia coli from Qom, Iran

OBJECTIVE: The emergence of metallo-β-lactamase-producing Enterobacteriaceae is a worldwide health concern. In this study, the first evaluation of MBL genes, bla(IMP) and bla(VIM), in Escherichia coli resistant to imipenem isolated from urine and blood specimens in Qom, Iran is described. Three hundred urine and blood specimens were analysed to detect the presence of E. coli. Resistance to imipenem and other antimicrobials was determined by disk diffusion and MIC. MBL production was screened using CDDT. PCR was also carried out to determine the presence of bla(IMP) and bla(VIM) genes in imipenem-resistant isolates. RESULTS: In total, 160 E. coli isolates were collected from March to May 2016. According to disk diffusion, high-level of resistance (20%) to cefotaxime was observed, whereas the lowest (1%) was detected for tetracycline. In addition, five isolates showed resistance to imipenem with a MIC ≥ 4 µg/mL. CDDT test confirmed that five isolates were MBL-producing strains, but no bla(IMP) and bla(VIM) genes were detected. Results of this study show a very low level of resistance to imipenem in our geographical area.