title: Outcomes of Clostridium difficile-associated disease treated with metronidazole or vancomycin before and after the emergence of NAP1/027.
abstract: OBJECTIVE
  To reassess the comparative efficacy of vancomycin versus metronidazole in the treatment of Clostridium difficile-associated disease (CDAD) after the emergence in 2003 of the hypervirulent NAP1/027 strain.
  
  
  METHODS
  A retrospective cohort study was conducted in a tertiary-care Canadian hospital among 1,616 patients treated initially with metronidazole (N=1,360), vancomycin (N=219), or both (N=37), between 1991 and 2006, and followed for 60 days after diagnosis. Primary outcome was severe/complicated CDAD (SC-CDAD) defined as any of: (a) death within 30 days, (b) septic shock, (c) megacolon, (d) perforation, or (e) emergency colectomy. Adjusted odds ratios (AOR) and their 95% confidence intervals (CI) were calculated, stratifying into pre-epidemic (1991-2002) and epidemic (2003-2006) periods. Secondary outcome was recurrence within 60 days.
  
  
  RESULTS
  Risk factors for SC-CDAD were the same in both periods: age>or=65 yr, male sex, immunosuppression, hospital acquisition, tube feeding, short duration of diarrhea, fever, elevated leukocytosis, or creatinine. Adjusting for confounders and using metronidazole therapy as baseline, vancomycin therapy was associated with a lower probability of developing SC-CDAD in 1991-2002 (AOR 0.21, 95% CI 0.05-0.99, P=0.048) but not during 2003-2006 (AOR 0.90, 95% CI 0.53-1.55, P=0.71). For both metronidazole and vancomycin, risk of recurrence increased in 2003-2004 but decreased in 2005-2006.
  
  
  CONCLUSIONS
  Loss of superiority of vancomycin over metronidazole coincided with the emergence of NAP1/027. Toxin hyperproduction by NAP1/027 might be such that the disease follows its natural course. Novel therapeutic approaches are needed. The higher risk of recurrence in 2003-2004 probably reflected reinfections rather than relapses.
authors: Department of Microbiology and Infectious Diseases, University of Sherbrooke, Sherbrooke, Quebec, Canada.
authors: Jacques
authors: J
authors: Pépin
authors: Louis
authors: L
authors: Valiquette
authors: Sandra
authors: S
authors: Gagnon
authors: Sophie
authors: S
authors: Routhier
authors: Isabel
authors: I
authors: Brazeau
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016009:Chi-Square Distribution; D016360:Clostridioides difficile / Q000302:isolation & purification / Q000472:pathogenicity*; D004761:Enterocolitis, Pseudomembranous / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use*; D011792:Quebec / Q000453:epidemiology; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014640:Vancomycin / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D014640:Vancomycin