Detection of extended spectrum β lactamases in Escherichia coli and Klebsiella Pneumoniae with E test

OBJECTIVE To detect the extended spectrum β lactamases (ESBLs) and the resistance of aztreonam and the third generation cephalosporins to clinical isolates of E. coli and K pneumoniae. METHODS 107 strains of E.coli and 78 strains of K.pneumoniae were isolated from clinical specimens and detected with disk diffusion method and ESBLs were measured in suspected straims by E test. RESULTS ESBLs detection rate by E test was 15.89% in resiistant strains of E.coli and 24.35% in K. pneumoniae. The resistance rates of E.coli were: 2.8% for aztreonam, 7.5% for ceftriaxone, 8.4% for cefotaxime, 9.3% for ceftazidime and 15.0% for cefoperazone. The resistance rates of K.pneumoniae were: 34.6% for aztreonam, 30.8% for ceftriaxone, 23.1% for cefotaxime, 26.9% for ceftazidime and 23.1% for cefoperazone. CONCLUSION The susceptibility rate of E.coil was higher than that of K.pneumoniae and the strains of K.pneumoniae producing ESBLs were more than that of E.coil strains.