title: Emergence of antimicrobial resistance in gram-negative bacilli causing bacteremia during therapy.
abstract: Treatment of serious infections caused by gram-negative bacilli with beta-lactam antimicrobial agents can induce Class I beta-lactamase production. This phenomenon can result in resistant microorganisms, and has been postulated to be a cause of therapeutic failure. The charts of patients bacteremic with Pseudomonas aeruginosa, Serratia marcescens, Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Providencia species (n = 120) during a 3-year period were reviewed to determine how common the emergence of resistance was, and to determine if in vitro susceptibility testing was a reliable therapeutic guide. Emergence of resistance was believed to occur when a subsequent bacteremic isolate showed at least a fourfold increase in minimum inhibitory concentration accompanied by a change of interpretive susceptibility category. In the group of patients who survived at least 48 hours that received beta-lactam therapy (n = 76), one case of emergence of resistance was identified (1.3%). Emergence of resistance to beta-lactam antimicrobial agents did not commonly cause therapeutic failure at our institution, and susceptibility testing of gram-negative bacilli by usual methods was a reliable guide to antimicrobial therapy.
authors.affiliation: Department of Pathology and Laboratory Medicine, Akron City Hospital, Ohio.
authors.forename: J D
authors.initials: JD
authors.lastname: Siebert
authors.forename: R B
authors.initials: RB
authors.lastname: Thomson
authors.forename: J S
authors.initials: JS
authors.lastname: Tan
authors.forename: L W
authors.initials: LW
authors.lastname: Gerson
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy*; D004352:Drug Resistance, Microbial; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D007769:Lactams; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents; D007769:Lactams