title: Population-based assessment of the incidence, risk factors, and outcomes of anaerobic bloodstream infections.
abstract: BACKGROUND
  Anaerobes are a relatively uncommon but important cause of bloodstream infection. However, their epidemiology has not been well defined in non-selected populations. We sought to describe the incidence of, risk factors for, and outcomes associated with anaerobic bacteremia.
  
  
  METHODS
  Population-based surveillance for bacteremia with anaerobic microorganisms was conducted in the Calgary area (population 1.2 million) during the period from 2000 to 2008.
  
  
  RESULTS
  A total of 904 incident cases were identified, for an overall population incidence of 8.7 per 100,000 per year; 231 (26 %) were nosocomial, 300 (33 %) were healthcare-associated community-onset, and 373 (41 %) were community-acquired. Elderly males were at the greatest risk. The most common pathogens identified were: Bacteroides fragilis group (3.6 per 100,000), Clostridium (non-perfringens) spp. (1.1 per 100,000), Peptostreptococcus spp. (0.9 per 100,000), and Clostridium perfringens (0.7 per 100,000). Non-susceptibility to metronidazole was 2 %, to clindamycin 17 %, and to penicillin 42 %. Relative to the general population, risk factors for anaerobic bloodstream infection included: male sex, increasing age, a prior diagnosis of cancer, chronic liver disease, heart disease, diabetes mellitus, stroke, inflammatory bowel disease, human immunodeficiency virus (HIV) infection, chronic obstructive pulmonary disease (COPD), and/or hemodialysis-dependent chronic renal failure (HDCRF). The 30-day mortality was 20 %. Increasing age, nosocomial acquisition, presence of malignancy, and several other co-morbid illnesses were independently associated with an increased risk of death.
  
  
  CONCLUSIONS
  Anaerobic bloodstream infection is responsible for a significant burden of disease in general populations. The data herein establish the extent to which anaerobes contribute to morbidity and subsequent mortality. This information is key in developing preventative, empiric treatment and research priorities.
authors.affiliation: Department of Medicine, Alberta Health Services, The University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
authors.forename: J T
authors.initials: JT
authors.lastname: Ngo
authors.forename: M D
authors.initials: MD
authors.lastname: Parkins
authors.forename: D B
authors.initials: DB
authors.lastname: Gregson
authors.forename: J D D
authors.initials: JD
authors.lastname: Pitout
authors.forename: T
authors.initials: T
authors.lastname: Ross
authors.forename: D L
authors.initials: DL
authors.lastname: Church
authors.forename: K B
authors.initials: KB
authors.lastname: Laupland
mesh_terms: D000416:Alberta / Q000453:epidemiology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D001421:Bacteria, Anaerobic / Q000145:classification / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D006801:Humans; D015994:Incidence; D011159:Population Surveillance; D012189:Retrospective Studies; D012307:Risk Factors