Antimicrobial resistance of 235 strains of Escherichia coli isolated from patients with bloodstream infection

Abstract:

ObjectiveTo investigate antimicrobial resistance of Escherichia coli (E.coli) isolated from patients with bloodstream infection, and provide evidence for rational use of antimicrobial agents in clinical practice.MethodsBacT/Alert automated blood culture system and VITEK 2 automated identification system were used for bacterial culture and identification. Antimicrobial susceptibility testing and detection of extendedspectrum βlactamases (ESBLs)producing strains were performed by KirbyBauer method. ResultsFrom 2009 to 2011, a total of 235 strains of E.coli were isolated from patients with bloodstream infection, 90 (38.30%) of which were ESBLs positive strains. The resistant rates of ESBLsproducing strains to ampicillin, cefotaxime and ceftriaxone were all 100%, but susceptibility rate to imipenem/cilastatin and meropenem were all 100%, to cefmetazole and amikacin were >90%. The resistant rate of nonESBLsproducing strains to ampicillin was the highest (70.63%), susceptibility rate to imipenem/cilastatin and meropenem were both 100%, to amikacin, cefotaxime, and cefmetazole were all >95%. The resistant rate of ESBLsproducing strains was significantly higher than that of the nonESBLsproducing strains. Of βlactamase inhibitor, only susceptibility rate of ESBLsproducing E.coli to cefoperazone/sulbactam was>90%,  susceptibility rates to piperacillin / tazobactam and ticarcillin/clavulanate were both<80%. ConclusionAntimicrobial resistant rate of ESBLsproducing strains causing bloodstream infection is high, individualized treatment strategies should be made according to antimicrobial resistance of bacteria causing infection in patients.