title: Association between  Clostridium difficile infection  and antimicrobial usage in  a large group of English  hospitals.
abstract: OBJECTIVE
  This study aimed to determine the association between the reduction in the number of Clostridium difficile infection (CDI) cases reported by the English National Health Service (NHS) hospitals and concurrent antimicrobial use.
  
  
  METHODS
  A retrospective ecological study for January 2005 to December 2008 was conducted using data from 26 of the 29 NHS trusts (i.e. a trust manages one or more hospitals) located in the North West Strategic Health Authority of England. Antimicrobial use data, for patients of all ages, were provided by IMS Health, and CDI case data for patients aged ≥65 years were provided by the Health Protection Agency. Antimicrobial use was converted into defined daily doses (DDDs). The overall association between antimicrobial use and CDI for the trusts was investigated using multilevel models.
  
  
  RESULTS
  Our study shows a positive significant association between the CDI cases and the use of the following antimicrobials: ‘third-generation cephalosporins’ [11.62 CDI cases per 1000 DDDs; 95% confidence interval (CI), 5.92–17.31]; ‘fluoroquinolones’ (4.79 CDI cases per 1000 DDDs; 95% CI, 2.83–6.74); and ‘second-generation cephalosporins’ (4.25 CDI cases per 1000 DDDs; 95% CI, 1.66–6.83). The strength of this association was not significantly different (95% CI) among the antimicrobial groups.
  
  
  CONCLUSIONS
  This study shows that the reduction in the number of CDI cases reported by the English NHS hospitals is associated with concurrent reductions in antimicrobial use. This means that the number of CDI cases over time decreased in a similar fashion to the usage of various antimicrobials.
authors.forename: Joao B
authors.initials: JB
authors.lastname: Pereira
authors.forename: Tracey M
authors.initials: TM
authors.lastname: Farragher
authors.forename: Mary P
authors.initials: MP
authors.lastname: Tully
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jonathan Cooke
mesh_terms: D000890:Anti-Infective Agents / Q000009:adverse effects*; D004739:England; D004761:Enterocolitis, Pseudomembranous / Q000453:epidemiology*; D006761:Hospitals; D006801:Humans; D012189:Retrospective Studies
chemical_list: D000890:Anti-Infective Agents