title: A hospital outbreak of high-level beta-lactam-resistant Enterobacter spp.: association more with ampicillin and cephalosporin therapy than with nosocomial transmission.
abstract: We studied an 8 month outbreak of a 7-fold increased isolation rate of high-level beta-lactam-resistant Enterobacter spp. from clinical infections (20 patients, 22 isolates: 20 E. cloacae, 2 E. aerogenes). In a case-control analysis the occurrence of resistant Enterobacter spp. was found to be associated with treatment with multiple antibiotics (p = 0.03), broad-spectrum beta-lactam agents (p = 0.0001) including ampicillin (p = 0.04), and cephalosporins (cefuroxime and cefotaxime, p = 0.004). Biochemical fingerprinting and pulsed-field gel electrophoresis (PFGE) typing showed no identity between the resistant isolates, indicating that neither cross-infection nor nosocomial transmission from a common source was the immediate cause of the problem. The outbreak was not paralleled by the overall Enterobacter spp. isolation rate or the antibiotic usage pattern in the hospital. Thus, the underlying cause of the outbreak remained obscure.
authors.affiliation: Malmö County Hospital, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Walder
authors.forename: S
authors.initials: S
authors.lastname: Haeggman
authors.forename: K
authors.initials: K
authors.lastname: Tullus
authors.forename: L G
authors.initials: LG
authors.lastname: Burman
mesh_terms: D000368:Aged; D000667:Ampicillin / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D002511:Cephalosporins / Q000627:therapeutic use*; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission*; D004269:DNA, Bacterial / Q000032:analysis; D004196:Disease Outbreaks; D004359:Drug Therapy, Combination; D016521:Electrophoresis, Gel, Pulsed-Field; D004754:Enterobacter / Q000187:drug effects* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy* / Q000453:epidemiology*; D005260:Female; D006761:Hospitals; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010406:Penicillins / Q000627:therapeutic use*; D012150:Polymorphism, Restriction Fragment Length; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D010406:Penicillins; D000667:Ampicillin