Occurrence of extended-spectrum and AmpC beta-lactamases in bloodstream isolates of Klebsiella pneumoniae: isolates harbor plasmid-mediated FOX-5 and ACT-1 AmpC beta-lactamases.

ABSTRACT: We tested 190 Klebsiella pneumoniae bloodstream isolates recovered from 189 patients in 30 U.S. hospitals in 23 states to determine the occurrence of extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase producers. Based on growth inhibition by clavulanic acid by disk and MIC test methods, 18 (9.5%) of the isolates produced ESBLs. Although the disk diffusion method with standard breakpoints identified 28 cefoxitin-nonsusceptible isolates, only 5 (18%) of these were confirmed as AmpC producers. Of two AmpC confirmatory tests, the three-dimensional extract test was easier to perform than was the double-disk approximation test using a novel inhibitor, Syn2190. Three of the five AmpC producers carried the bla(FOX-5) gene, while the other two isolates harbored the bla(ACT-1) gene. All

SUBMITTER: Coudron PE 

PROVIDER: S-EPMC149714 | biostudies-literature | 2003 Feb

REPOSITORIES: biostudies-literature