title: Case fatality associated with a hypervirulent strain in patients with culture-positive Clostridium difficile infection: a retrospective population-based study.
abstract: BACKGROUND
  Clostridium difficile is a major infectious cause of healthcare-associated diarrhea. The epidemiology of C. difficile infection (CDI) is changing, with evidence of increased incidence and severity. The first patient with a hypervirulent strain type in Pirkanmaa Hospital District, Finland was reported in September 2008.
  
  
  METHODS
  We reviewed all culture-positive C. difficile episodes that occurred in Pirkanmaa Hospital District during the period September 2008 to May 2010.
  
  
  RESULTS
  A total of 780 episodes of C. difficile occurred in 622 patients. A hypervirulent strain caused 14.2% of all episodes. The day 30 case fatality associated with CDI was 8.5% in episodes with a non-hypervirulent strain and 20.7% in episodes with a hypervirulent strain type (p<0.001, odds ratio 2.8, 95% confidence interval 1.6-4.8). The median age among those infected by a hypervirulent strain was higher than among those infected by a non-hypervirulent strain (83 vs. 75 years, p<0.001). Hypervirulent strain type remained a significant factor associated with case fatality in a logistic regression model. Blood leukocytes were significantly higher in episodes due to a hypervirulent strain (11.0 vs. 9.4 × 10(9)/l, p=0.007). Blood leukocytes and C-reactive protein (CRP) on the day of diagnosis were significantly higher in non-survivors compared to survivors in CDI (13.2 vs. 9.6 × 10(9)/l, p=0.009, and 106.0 vs. 79.4 mg/l, p<0.001, respectively).
  
  
  CONCLUSIONS
  Infection due to a hypervirulent strain is a factor associated with increased case fatality in CDI. Blood leukocytes are significantly higher in CDI caused by a hypervirulent strain. Leukocyte count and CRP are useful prognostic biomarkers in patients with CDI.
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, Box 2000, FI-33521 Tampere, Finland. Reetta.Huttunen@uta.fi
authors.forename: Reetta
authors.initials: R
authors.lastname: Huttunen
authors.forename: Risto
authors.initials: R
authors.lastname: Vuento
authors.forename: Jaana
authors.initials: J
authors.lastname: Syrjänen
authors.forename: Päivi
authors.initials: P
authors.lastname: Tissari
authors.forename: Janne
authors.initials: J
authors.lastname: Aittoniemi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002097:C-Reactive Protein / Q000378:metabolism; D016360:Clostridioides difficile / Q000472:pathogenicity*; D003015:Clostridium Infections / Q000382:microbiology / Q000401:mortality*; D004761:Enterocolitis, Pseudomembranous / Q000382:microbiology / Q000401:mortality*; D005260:Female; D005387:Finland; D006801:Humans; D007958:Leukocyte Count; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009026:Mortality; D011379:Prognosis; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein