Extended spectrum Beta-lactamases: prevalênce and comparison of screening for detection

Abstract

The Extended Spectrum Beta-lactamases may produce hidden but clinicaly significant resistance to expanded-spectrum cephalosporins and aztreonam. This enzimes are produced mainly by Klebsiella and Escherichia coli. Modified interpretive criteria for key antibiotics or the use of special antimicrobial susceptibility tests should be used to increase the sensitivity of ESBL detection 735 isolates of Escherichia coli and 192 of klebsiella sp were studied for determine the prevalence of ESBL in HURNP The results obtained indicate 2,99 % of E. coli and 36,46 % of Klebsiella sp that encode for resistance to broad-spectrum beta-Iactam antibiotics. Using a set of 156 strains of E. coli and 74 of Klebsiella sp, we compared three screening methods for ESBL detection: a double-disk synergy test, disk diffusion (both test were performed with ceftazidime, cefotaxime and aztreonam) and MicroScan microdilution panels (performed with ceftazidime and ceftriaxone e/ou cefotaxime). The results of this study suggest that three screening methods can be equally used by clinical laboratories as an indicator of extended-spectrum beta-lactamases. in isolates of E. coli and Klebsiella sp.