title: Nosocomial Gram-negative bacteremia in intensive care: epidemiology, antimicrobial susceptibilities, and outcomes.
abstract: OBJECTIVE
  To describe the epidemiology, antimicrobial susceptibilities, treatment, and outcomes of intensive care unit (ICU)-acquired Gram-negative bacteremia.
  
  
  METHODS
  Patients with ICU-acquired Gram-negative bacteremia from 2004 to 2012 were reviewed retrospectively. Independent predictors of mortality were examined using multivariable Cox regression.
  
  
  RESULTS
  Seventy-eight cases of ICU-acquired Gram-negative bacteremia occurred in 74 patients. The infection rate was 0.97/1000 patient-days. Mean patient age was 55 years, 62% were male. The most common admission diagnoses were respiratory failure (34%) and sepsis/septic shock (45%). Mortality was 35% at 30 days. The most common source of bacteremia was pneumonia (33%). Of 83 Gram-negative isolates, Escherichia coli (20%) and Pseudomonas aeruginosa (18%) were most common. For aerobic isolates, susceptibilities to ciprofloxacin (61%) and piperacillin/tazobactam (68%) were low. For pseudomonal isolates, susceptibilities to ciprofloxacin (53%), piperacillin/tazobactam (67%), and imipenem (53%) were equally disappointing. Adequate empiric antimicrobial therapy was prescribed in 85% of bacteremia cases. On multivariable analysis, adequate empiric therapy (adjusted hazard ratio (aHR) 0.38, 95% confidence interval (CI) 0.16-0.89), immune suppression (aHR 3.4, 95% CI 1.4-8.3), and coronary artery disease (aHR 4.5, 95% CI 1.7-11.9) were independently associated with 30-day mortality.
  
  
  CONCLUSIONS
  ICU-acquired Gram-negative bacteremia is associated with high mortality. Resistance to ciprofloxacin, piperacillin/tazobactam, and carbapenems was common. Coronary artery disease, immune suppression, and inadequate empiric antimicrobial therapy were independently associated with increased mortality.
authors.affiliation: Divisions of Critical Care Medicine and Infectious Diseases, Faculty of Medicine and Dentistry, University of Alberta, 2-124 Clinical Sciences Building, 8440-112 Street, Edmonton, AB, T6G 2B7, Canada. Electronic address: wsligl@ualberta.ca.
authors.forename: Wendy Irene
authors.initials: WI
authors.lastname: Sligl
authors.affiliation: Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Dragan
authors.affiliation: Division of Infectious Diseases, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Stephanie Wrenn
authors.initials: SW
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D003422:Critical Care; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000453:epidemiology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobial resistance; Bacteremia; Critical care; Gram-negative; Intensive care; Nosocomial infection