title: Outbreak of ampicillin-resistant Enterococcus faecium--risk factors for faecal colonisation.
abstract: Since January 1995 there has been a nosocomial outbreak at Haukeland University Hospital involving more than 330 patients with clinical infections caused by ampicillin-resistant Enterococcus faecium (ARE) (minimum inhibitory concentration > or =32 mg/l). Rectal carriage of ARE was initially observed on two medical wards only. Here the ARE colonisation rate has remained high. To assess risk factors for ARE colonisation we performed a case-control study including 37 rectal carriers of ARE and 83 non-carriers on these wards. Significant differences were found between cases and controls with respect to the mean number of days on antimicrobial treatment (13.3 for carriers, 5.5 for non-carriers, p<0.001), mean number of different antibiotics prescribed (2.8 for carriers, 2.1 for non-carriers, p= 0.008) and mean number of days in hospital (18.4 vs 10.2, p=0.001). Unadjusted statistical analysis showed that several antibiotics were risk factors for ARE carriage. Logistic regression analysis showed that fluoroquinolone prescription (OR=3.5, p=0.01) and more than 10 days of antibiotic use (OR= 3.3, p=0.01) were significant risk factors. An additional follow-up screening of previous carriers revealed no colonisation 8 to 36 (median 9) months after discharge from hospital (n=17). Prolonged antimicrobial therapy and broad-spectrum antibiotics seem to facilitate nosocomial ARE colonisation.
authors.affiliation: Department for Infection Control, Haukeland Hospital and University of Bergen, Norway. scmo@haukeland.no
authors.forename: S C
authors.initials: SC
authors.lastname: Mohn
authors.forename: S
authors.initials: S
authors.lastname: Harthug
authors.forename: N
authors.initials: N
authors.lastname: Langeland
mesh_terms: D000668:Ampicillin Resistance; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002353:Carrier State / Q000453:epidemiology*; D016022:Case-Control Studies; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000635:transmission; D004196:Disease Outbreaks; D016984:Enterococcus faecium / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000635:transmission; D006746:Hospital Bed Capacity, 500 and over; D006785:Hospitals, University; D006801:Humans; D007902:Length of Stay; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D012044:Regression Analysis; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents