Study of the best detection substrate and antibiotic resistance in clinical of Escherichia coli and klebsieua pneumoniae producing extended-spectrum beta-lactamases

Objective To investigate the prevalence of strains producing ESBLs among Escherichia coil and Klebsieua pneumoniae, look for the best detection substrate of these strains and determine the antibiotic resistance of them. Methods 248 strains of E. coli and 97 strains of K. pn. from January to October,2002 were investigate for production of extended-spectrum β-lactamases(ESBLs) by phenotypic screening and confirmatory test provided by the National Committee for Clinical Laboratory Standatrds; Compared the result of the phenotypic screening and confirmatory test to discuss the best detection substrate of these strains; 16 kind of antibiotics were selected for antimicrobial susceptibility test for the resistance. Result 14.5%(36/248) of E. coli,25. 8% (25/97) of K. pneumoniae produced ESBLs;The best detection substrate was cefotaxime, follow cetriaxone, aztreonam and cefpodoxime; All tested strains were susceptible to imipenem, the resistance rate of aminoglycosides, cefoxitin, cefoperazone/β-lactamase inhibitor combinations was lower than other antibiotics. Conclusions Cefotaxime was the detection substrate of ESBLs; To deal with the ESBLs-producing strains, such antibiotics as imipenem, cefoxitin, β-lactamase inhibitor combinations and others which are sensitive to such strains can be used.