title: Cycling empirical antimicrobial agents to prevent emergence of antimicrobial-resistant Gram-negative bacteria among intensive care unit patients.
abstract: OBJECTIVE
  To determine the impact of the rotation of antimicrobial agents on the rates of infection, intestinal colonization, and acquisition with antimicrobial-resistant Gram-negative bacteria.
  
  
  METHODS
  Pre- and postintervention design.
  
  
  METHODS
  A 19-bed, medical intensive care unit.
  
  
  METHODS
  Individuals admitted to the study unit for >48 hrs.
  
  
  METHODS
  After a 5-month baseline observation period, four classes of antimicrobial agents with Gram-negative activity were cycled at 3- to 4-month intervals for 24 months.
  
  
  RESULTS
  The primary outcome was the acquisition rate of antimicrobial resistance among Enterobacteriaceae and Pseudomonas aeruginosa obtained from rectal swab cultures performed on admission, weekly during the patients' stay, and at discharge. Rates and microbiology of nosocomial bloodstream infections and ventilator-associated pneumonia were also compared between baseline and cycling periods. The cycling program resulted in a significant change in prescribing practices; the predominant agent used changed with each cycle. Among study patients who were not already colonized with a resistant organism, the rate of acquisition of enteric colonization with bacteria resistant to any of the target drugs remained stable during the cycling period for P. aeruginosa (relative rate, 0.96; 95% confidence Interval, 0.47-2.16) and Enterobacteriaceae (relative rate, 1.57; 95% confidence interval, 0.80-3.43). Hospital-wide, P. aeruginosa from routine clinical cultures resistant to the target drugs increased during the cycling period. The proportion of Gram-negative bacteria isolated from cases of nosocomial bloodstream infection (29% baseline vs. 26% cycling; p = .11) and ventilator-associated pneumonia (80% vs. 41%; p = .06) did not significantly differ.
  
  
  CONCLUSIONS
  In this study, antimicrobial cycling did not result in a significant change in enteric acquisition of resistant Gram-negative bacteria among intensive care unit patients.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA. dwarren@im.wustl.edu
authors.forename: David K
authors.initials: DK
authors.lastname: Warren
authors.forename: Holly A
authors.initials: HA
authors.lastname: Hill
authors.forename: Liana R
authors.initials: LR
authors.lastname: Merz
authors.forename: Marin H
authors.initials: MH
authors.lastname: Kollef
authors.forename: Mary K
authors.initials: MK
authors.lastname: Hayden
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Fraser
authors.forename: Scott K
authors.initials: SK
authors.lastname: Fridkin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016001:Confidence Intervals; D016638:Critical Illness; D003428:Cross Infection / Q000188:drug therapy* / Q000382:microbiology* / Q000401:mortality / Q000517:prevention & control; D024881:Drug Resistance, Bacterial; D005260:Female; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000401:mortality / Q000517:prevention & control; D006784:Hospitals, Teaching; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011336:Probability; D011379:Prognosis; D018570:Risk Assessment; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents