Resistant phenotype of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumonia and comparison of four detecting methods

Objective:To investigate the prevalence of drug resistant phenotype of extended spectrum beta lactamases (ESBLs) producing E. coli and K. pneumonia and to compare the four of detecting methods for ESBLs . Methods:After the suspected E. coli and K. pneumonia were isolated from ESBLs, the disc diffusion confirmatory test, double disc synergy test, GNS NT sensitive card and Etest ESBLs test were used for experimental comparison. According to the GNS NT sensitive card, drug resistance condition was counted. Results:Among 316 strains, 118 were suspected producing ESBLs and 96 of them were confirmed by the disc diffusion confirmatory test, and the synergy phenomenon in 90 strains was confirmed by the synergy test. Twenty eight strains were confirmed producing ESBLs, 24 strains showed positive respectively by GNS NT card and Etest tests. The resistance rate of beta lactams such as aztreonam (ATN), cefotaxime (CTX), ceftriaxone (CRO), ceftazidime (CTD) and cefpodoxime (CPO) are higher, but imipenem (IMP) is sensitive. The resistance rate of non beta lactam agents is also high. Conclusion:The positive accordance rate of the confirmatory test and double disc synergy test is lower. The sensitivity of GNS NT card and Etest ESBLs is lower than the above two tests. ANT, CTX, CRO and CPO are the suitable substances for the determination of the substrates of ESBLs. The sensitivity of nitrofurans, quinlones, aminoglycosides and sulfonamides for producing ESBLs strains is poorer.