title: Imipenem resistance in Enterobacter.
abstract: Blood cultures obtained on two separate occasions from a 37-year-old male who received multiple antibiotics (including imipenem) for treatment of repeated episodes of intraabdominal abscesses and bacteremia yielded two isolates of Enterobacter with reduced susceptibility to imipenem, extended-spectrum cephalosporins, penicillins and aztreonam. Both isolates were unstable, giving rise to different colony types, each of which produced a single, non-inducible Bush group 1 beta-lactamase (pI = 9.6) that hydrolyzed imipenem. Outer membrane proteins were analyzed but no differences were detected between strains with different levels of imipenem resistance. Three-dimensional tests performed in conjunction with disk diffusion susceptibility tests provided a rapid and convenient means of detecting the production of imipenem-hydrolyzing enzymes by the Enterobacter strains. These isolates provided additional evidence that overproduction of the group 1 cephalosporinase of Enterobacter can contribute to resistance to imipenem.
authors.affiliation: Department of Medical Microbiology, Creighton University School of Medicine, Omaha, Nebraska 68178.
authors.forename: K S
authors.initials: KS
authors.lastname: Thomson
authors.forename: C C
authors.initials: CC
authors.lastname: Sanders
authors.forename: H
authors.initials: H
authors.lastname: Chmel
mesh_terms: D000328:Adult; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology*; D002510:Cephalosporinase / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004754:Enterobacter / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D015378:Imipenem / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008826:Microbial Sensitivity Tests
chemical_list: D015378:Imipenem; D002510:Cephalosporinase