title: Low-level colonization and infection with ciprofloxacin-resistant gram-negative bacilli in a skilled nursing facility.
abstract: BACKGROUND
  We report a 1-year surveillance study that evaluates colonization and infection with ciprofloxacin-resistant gram-negative bacilli (CR GNB) and the relation to quinolone use and other possible risk factors in a proprietary skilled nursing facility (SNF) with no history of outbreaks.
  
  
  METHODS
  Rectal swabs obtained quarterly were streaked on MacConkey agar with ciprofloxacin discs (5 microg) to screen for CR GNB and later were speciated and the antimicrobial susceptibilities were confirmed by standardized disc-diffusion tests.
  
  
  RESULTS
  The mean prevalence of CR GNB colonization was 2.6% (range 0.9% to 5.3%). The colonization frequency was higher in the last survey than it was in the first survey. CR GNB-colonized strains included Pseudomonas species (21%), but more than half were non-Pseudomonas enterics such as Acinetobacter baumannii (25%), Proteus mirabilis (17%), and Providencia stuartii (13%). None of the patients who had colonization with CR GNB had subsequent infections with the same species. Patients with colonization had more exposure to ciprofloxacin and they were more likely to have been recently admitted from an acute-care hospital and have decubitus ulcers. During the study period, of 336 patients surveyed, 98 (29%) patients developed suspected infections and cultures were done; the infection rate was 4.7 per 1000 patient days. Of these infected patients, 59 (60%) were infected by GNBs; the infection rate was 2.3 per 1000 patient days. Nineteen percent of the GNB infections were treated with a quinolone. (Overall, quinolones constituted about 17% of antibiotic usage in the SNF). Only 3 (5%) of the patients infected with GNB were infected with CR GNB, including Pseudomonas and Providenci a species. The CR GNB infections involved multiple sites, multiple organisms, and long length of stay in the SNF.
  
  
  CONCLUSIONS
  The findings indicate that in this community SNF, a low frequency of colonization or infection with CR GNB existed. Whether continued moderate use of quinolones will lead to increasing levels of CR GNB will require further study.
authors.affiliation: Infectious Disease Division, Department of Medicine, University of California Irvine, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Lee
authors.forename: T
authors.initials: T
authors.lastname: Cesario
authors.forename: V
authors.initials: V
authors.lastname: McCauley
authors.forename: L
authors.initials: L
authors.lastname: Flionis
authors.forename: A
authors.initials: A
authors.lastname: Pax
authors.forename: L
authors.initials: L
authors.lastname: Thrupp
mesh_terms: D000368:Aged; D000890:Anti-Infective Agents / Q000627:therapeutic use; D002140:California; D002353:Carrier State / Q000188:drug therapy / Q000382:microbiology*; D002939:Ciprofloxacin / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D017053:Infection Control; D008137:Longitudinal Studies; D008297:Male; D008403:Mass Screening; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012307:Risk Factors; D012866:Skilled Nursing Facilities
chemical_list: D000890:Anti-Infective Agents; D002939:Ciprofloxacin