Comparison of some tests used for detection of extended spectrum beta lactamases (ESBL) among Enterobacteriaceae and determination of ESBL prevalence

COMPARISON OF SOME TESTS USED FOR DETECTION OF EXTENDEDSPECTRUM BETA LACTAMASES (ESBL) AMONG ENTEROBACTERIACEAESTRAINS AND DETERMINATION OF ESBL PREVALENCEAYŞE B LGE S PAHSeveral tests were developed by different investigators and some widely used byclinical laboratories to detect ESBL?s among Gram negative bacilli. In this study,combineddisk diffusion, double disk synergy, modified three dimensional, spot inoculation, inhibitorpotentiated disk diffusion and microdilution tests were evaluated for their abilities to detectproduction of extended spectrum beta lactamases(ESBL). And also ESBL prevalence wasdetermined among Enterobacteriaceae strains isolated from different clinical specimens inGazi University hospital microbiology laboratory.As a result, 92 (23.8%) of 386 Enterobacteriaceae isolates were found to produceESBL. The ESBL production rates in K.pneumoniae, E.coli, K.oxytoca and other strains were38.2%, 23.4%, 9.1% and14.2% respectively.Compared to combined disk diffusion test, the sensitivities of double disk synergy test,inhibitor potantiated disk diffusion test, microdilution test, modified three dimensional testand spot inoculation test were 100%, 98.9%, 98.9%, 95.7%, 93.5%, respectively.Accoring to data obtained from this study, it was concluded that double disk synergytest was a cheap, easy to perform, reliable test to detect ESBL?s in Gram negative bacilli inroutine clinical microbiology laboratories and also as sensitive as combined disk diffusion testrecommended by CLSI.