title: Outcomes in Documented Pseudomonas aeruginosa Bacteremia Treated with Intermittent IV Infusion of Ceftazidime, Meropenem, or Piperacillin-Tazobactam: A Retrospective Study.
abstract: BACKGROUND
  Pseudomonas aeruginosa, one of the leading causes of nosocomial gram-negative bloodstream infections, is particularly difficult to treat because of its multiple resistance mechanisms combined with a lack of novel antipseudomonal antibiotics. Despite knowledge of time-dependent killing with ß-lactam antibiotics, most hospitals in Canada currently administer ß-lactam antibiotics by intermittent rather than extended infusions.
  
  
  OBJECTIVE
  To determine clinical outcomes, microbiological outcomes, total hospital costs, and infection-related costs for patients with P. aeruginosa bacteremia who received intermittent IV administration of antipseudomonal ß-lactam antibiotics in a tertiary care institution.
  
  
  METHODS
  For this retrospective descriptive study, data were collected for patients who were admitted between March 1, 2005, and March 31, 2013, who had P. aeruginosa bacteremia during their admission, and who received at least 72 h of treatment with ceftazidime, meropenem, or piperacillin-tazobactam. Clinical and microbiological outcomes were determined, and total and infection-related hospital costs were calculated.
  
  
  RESULTS
  A total of 103 patients were included in the analysis, of whom 79 (77%) experienced clinical cure. In addition, bacterial eradication was achieved in 41 (87%) of the 47 patients with evaluable data for this outcome. Twenty-eight (27%) of the 103 patients died within 30 days of discontinuation of antipseudomonal ß-lactam antibiotic therapy. The median total cost of the hospital stay was $121 718, and the median infection-related cost was $29 697.
  
  
  CONCLUSIONS
  P. aeruginosa bacteremia is a clinically significant nosocomial infection that continues to cause considerable mortality and health care costs. To the authors' knowledge, no previous studies have calculated total and infection-related hospital costs for treatment of P. aeruginosa bacteremia with intermittent infusion of antipseudomonal ß-lactam antibiotics, with characterization of cost according to site of acquisition of the infection. This study may provide important baseline data for assessing the impact of implementing extended-infusion ß-lactam therapy, antimicrobial stewardship, and infection control strategies targeting P. aeruginosa infection in hospitalized patients.
authors.affiliation: BSc(Hons), BScPhm, ACPR, was, at the time of this study, a General Practice Pharmacy Resident at Sunnybrook Health Sciences Centre, Toronto, Ontario. She is now with the Department of Pharmacy, St Michael's Hospital, Toronto, Ontario.
authors.forename: Francine
authors.initials: F
authors.lastname: Kwee
authors.affiliation: BSc, BScPhm, ACPR, PharmD, FCSHP, is with the Department of Pharmacy, and Division of Infectious Diseases, Sunnybrook Health Sciences Centre, and the Leslie L Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario.
authors.forename: Sandra A N
authors.initials: SA
authors.lastname: Walker
authors.affiliation: BScPhm, ACPR, is with the Department of Pharmacy, Sunnybrook Health Sciences Centre, Toronto, Ontario.
authors.forename: Marion
authors.initials: M
authors.lastname: Elligsen
authors.affiliation: BSc, BScPhm, MSc, ACPR, is with the Department of Pharmacy, Sunnybrook Health Sciences Centre, Toronto, Ontario.
authors.forename: Lesley
authors.initials: L
authors.lastname: Palmay
authors.affiliation: MD, FRCPC, is with the Department of Microbiology and the Division of Infectious Diseases, Sunnybrook Health Sciences Centre, and the Faculty of Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Andrew
authors.initials: A
authors.lastname: Simor
authors.affiliation: MD, MSc, FRCPC, is with the Division of Infectious Diseases, Sunnybrook Health Sciences Centre, and the Faculty of Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Nick
authors.initials: N
authors.lastname: Daneman
keywords: Pseudomonas; Pseudomonas aeruginosa; bacteremia; ceftazidime; infectious disease; intermittent infusion; meropenem; outcomes; piperacillin–tazobactam