title: Duration of antibiotic therapy for critically ill patients with bloodstream infections: A retrospective cohort study.
abstract: BACKGROUND
  The optimal duration of antibiotic treatment for bloodstream infections is unknown and understudied.
  
  
  METHODS
  A retrospective cohort study of critically ill patients with bloodstream infections diagnosed in a tertiary care hospital between March 1, 2010 and March 31, 2011 was undertaken. The impact of patient, pathogen and infectious syndrome characteristics on selection of shorter (≤10 days) or longer (>10 days) treatment duration, and on the number of antibiotic-free days, was examined. The time profile of clinical response was evaluated over the first 14 days of treatment. Relapse, secondary infection and mortality rates were compared between those receiving shorter or longer treatment.
  
  
  RESULTS
  Among 100 critically ill patients with bloodstream infection, the median duration of antibiotic treatment was 11 days, but was highly variable (interquartile range 4.5 to 17 days). Predictors of longer treatment (fewer antibiotic-free days) included foci with established requirements for prolonged treatment, underlying respiratory tract focus, and infection with Staphylococcus aureus or Pseudomonas species. Predictors of shorter treatment (more antibiotic-free days) included vascular catheter source and bacteremia with coagulase-negative staphylococci. Temperature improvements plateaued after the first week; white blood cell counts, multiple organ dysfunction scores and vasopressor dependence continued to decline into the second week. Among 72 patients who survived to 10 days, clinical outcomes were similar between those receiving shorter and longer treatment.
  
  
  CONCLUSIONS
  Antibiotic treatment durations for patients with bloodstream infection are highly variable and often prolonged. A randomized trial is needed to determine the duration of treatment that will maximize cure while minimizing adverse consequences of antibiotics.
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Havey
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario ; Department of Critical Care Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario ; Trauma, Emergency and Critical Care Research Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Fowler
authors.affiliation: Trauma, Emergency and Critical Care Research Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario.
authors.forename: Ruxandra
authors.initials: R
authors.lastname: Pinto
authors.affiliation: Department of Pharmacy, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario.
authors.forename: Marion
authors.initials: M
authors.lastname: Elligsen
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario ; Trauma, Emergency and Critical Care Research Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario ; Division of Infectious Diseases, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario.
authors.forename: Nick
authors.initials: N
authors.lastname: Daneman
keywords: Antibacterials; Antibiotic stewardship; Bacteremia; Bacterial infections; Critical care