title: Community-associated Clostridium difficile infection among older people in Tayside, Scotland, is associated with antibiotic exposure and care home residence: cohort study with nested case-control.
abstract: OBJECTIVE
  To estimate the risks of community-associated Clostridium difficile infection (CA-CDI) among the population aged ≥ 65 years associated with antibiotic exposure and care home residence.
  
  
  METHODS
  We linked cases from a prospective study in Tayside, Scotland from 1 November 2008 to 31 October 2009 to population datasets to conduct a cohort study and a nested, matched (1 : 10 by age and gender) case-control study.
  
  
  RESULTS
  There were 79,039 eligible residents. CA-CDI incidence was 20.3/10,000 person years. In the cohort study, after adjustment, we found a significantly increasing risk of CA-CDI with increasing age and comorbidity, prior hospital admission, care home residence [hazard ratio (HR) 1.96, 95% CI 1.14-3.34] and baseline antibiotic exposure (1.94, 1.35-2.77). In separate adjusted models, '4C' antibiotics (clindamycin, co-amoxiclav, cephalosporins, ciprofloxacin; 2.75, 1.78-4.26) and fluoroquinolones (3.33, 1.95-5.67) had higher associated risks. We matched 62 CA-CDI cases without recent (prior 3 months) hospital admission to 620 controls. In adjusted logistic regression models, exposure to any antibiotics increased the risk of CA-CDI (OR 6.04, 95% CI 3.19-11.43). Exposure to 4C antibiotics or fluoroquinolones had higher associated risks: adjusted OR 11.60 (95% CI 5.57-24.15) and 13.04 (4.91-34.64), respectively. Risk of CA-CDI increased with cumulative antibiotic exposure. Subgroup analysis of 42 cases with C. difficile cultured and 420 controls amplified all associations between antibiotic exposure and CA-CDI. Care home residence independently increased the risk of CA-CDI in all models.
  
  
  CONCLUSIONS
  Our results have two important implications. First, they validate the classification of 4C antibiotics and fluoroquinolones in primary care as high risk for CA-CDI. Second, they demonstrate the importance of prior antibiotic exposure and place of residence for risk assessment by primary care prescribers.
authors.affiliation: Population Health Sciences Division, Medical Research Institute, University of Dundee, Mackenzie Building, Kirsty Semple Way, Dundee DD2 4BF, UK.
authors.forename: Charis A
authors.initials: CA
authors.lastname: Marwick
authors.forename: Ning
authors.initials: N
authors.lastname: Yu
authors.forename: Michael C
authors.initials: MC
authors.lastname: Lockhart
authors.forename: Christopher C
authors.initials: CC
authors.lastname: McGuigan
authors.forename: Camilla
authors.initials: C
authors.lastname: Wiuff
authors.forename: Peter G
authors.initials: PG
authors.lastname: Davey
authors.forename: Peter T
authors.initials: PT
authors.lastname: Donnan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use*; D016022:Case-Control Studies; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000453:epidemiology*; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009735:Nursing Homes; D011446:Prospective Studies; D018570:Risk Assessment; D012606:Scotland / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: antimicrobials; community-acquired infections; elderly; long-term care facilities; nursing homes; proton pump inhibitors