title: Clinical and microbiological characteristics of bloodstream infections due to AmpC β-lactamase producing Enterobacteriaceae: an active surveillance cohort in a large centralized Canadian region.
abstract: BACKGROUND
  The objective of this study was to describe the clinical and microbiological characteristics of bloodstream infections (BSIs) due to AmpC producing Enterobacteriaceae (AE) in a large centralized Canadian region over a 9-year period.
  
  
  METHODS
  An active surveillance cohort design in Calgary, Canada.
  
  
  RESULTS
  A cohort of 458 episodes of BSIs caused by AE was assembled for analysis. The majority of infections were of nosocomial origin with unknown sources. Enterobacter spp. was the most common species while BSIs due to Serratia spp. had a significant higher mortality when compared to other AE. Delays in empiric or definitive antibiotic therapy were not associated with a difference in outcome. However, patients that did not receive any empiric antimicrobial therapy had increased mortality (3/5; 60% vs. 57/453; 13%; p = 0.018) as did those that did not receive definitive therapy (6/17; 35% vs. 54/441; 12%; p = 0.015).
  
  
  CONCLUSIONS
  Delays in therapy were not associated with adverse outcomes although lack of active therapy was associated with increased mortality. A strategy for BSIs due to AE where β-lactam antibiotics (including oxyimino-cephalosporins) are used initially followed by a switch to non-β-lactam antibiotics once susceptibility results are available is effective.
authors.affiliation: Department of Community Health Sciences, University of Calgary, TRW Building 3rd Floor, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada. vikas.chaubey@albertahealthservices.ca.|Department of Medicine, Administration Office, Foothills Medical Centre - North Tower, University of Calgary, 9th Floor, 1403 - 29th Street NW, Calgary, AB, T2N 2T9, Canada. vikas.chaubey@albertahealthservices.ca.|FRCPC, MDCM, TRW Building, 3rd Floor, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada. vikas.chaubey@albertahealthservices.ca.
authors.forename: Vikas P
authors.initials: VP
authors.lastname: Chaubey
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. dr.johann.pitout@cls.ab.ca.|Department of Microbiology, Immunology and Infectious Diseases, Health Research Innovation Centre, University of Calgary, Room 4AA06, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada. dr.johann.pitout@cls.ab.ca.|Calgary Laboratory Services, Alberta Health Services, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. dr.johann.pitout@cls.ab.ca.
authors.forename: Johann D D
authors.initials: JD
authors.lastname: Pitout
authors.affiliation: Department of Medicine, Administration Office, Foothills Medical Centre - North Tower, University of Calgary, 9th Floor, 1403 - 29th Street NW, Calgary, AB, T2N 2T9, Canada. bruce.dalton@albertahealthservices.ca.|Department of Pharmacy Services, Alberta Health Services, Foothills Medical Centre, Rm 1080, 10th floor, 1403 29th St NW, Calgary, AB, T2N 2T8, Canada. bruce.dalton@albertahealthservices.ca.
authors.forename: Bruce
authors.initials: B
authors.lastname: Dalton
authors.affiliation: Department of Medicine, Administration Office, Foothills Medical Centre - North Tower, University of Calgary, 9th Floor, 1403 - 29th Street NW, Calgary, AB, T2N 2T9, Canada. Dan.Gregson@cls.ab.ca.|Department of Pathology and Laboratory Medicine, University of Calgary, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. Dan.Gregson@cls.ab.ca.|Calgary Laboratory Services, Alberta Health Services, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. Dan.Gregson@cls.ab.ca.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Gregson
authors.affiliation: Calgary Laboratory Services, Alberta Health Services, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. terry.ross@cls.ab.ca.
authors.forename: Terry
authors.initials: T
authors.lastname: Ross
authors.affiliation: Department of Community Health Sciences, University of Calgary, TRW Building 3rd Floor, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada. klaupland@gmail.com.|Department of Medicine, Administration Office, Foothills Medical Centre - North Tower, University of Calgary, 9th Floor, 1403 - 29th Street NW, Calgary, AB, T2N 2T9, Canada. klaupland@gmail.com.|Department of Pathology and Laboratory Medicine, University of Calgary, Diagnostic & Scientific Centre 9, 3535 Research Road NW, Calgary, AB, T2L 2K8, Canada. klaupland@gmail.com.|Centre for Antimicrobial Resistance, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB, T2N 4N1, Canada. klaupland@gmail.com.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
mesh_terms: D000328:Adult; D000368:Aged; D000416:Alberta / Q000453:epidemiology; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000378:metabolism; D015331:Cohort Studies; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000378:metabolism; D047090:beta-Lactams / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D047090:beta-Lactams; C048795:AmpC beta-lactamases; D001618:beta-Lactamases