title: A predominantly clonal multi-institutional outbreak of Clostridium difficile-associated diarrhea with high morbidity and mortality.
abstract: BACKGROUND
  In March 2003, several hospitals in Quebec, Canada, noted a marked increase in the incidence of Clostridium difficile-associated diarrhea.
  
  
  METHODS
  In 2004 we conducted a prospective study at 12 Quebec hospitals to determine the incidence of nosocomial C. difficile-associated diarrhea and its complications and a case-control study to identify risk factors for the disease. Isolates of C. difficile were typed by pulsed-field gel electrophoresis and analyzed for binary toxin genes and partial deletions in the toxin A and B repressor gene tcdC. Antimicrobial susceptibility was evaluated in a subgroup of isolates.
  
  
  RESULTS
  A total of 1703 patients with 1719 episodes of nosocomial C. difficile-associated diarrhea were identified. The incidence was 22.5 per 1000 admissions. The 30-day attributable mortality rate was 6.9 percent. Case patients were more likely than matched controls to have received fluoroquinolones (odds ratio, 3.9; 95 percent confidence interval, 2.3 to 6.6) or cephalosporins (odds ratio, 3.8; 95 percent confidence interval, 2.2 to 6.6). A predominant strain, resistant to fluoroquinolones, was found in 129 of 157 isolates (82.2 percent), and the binary toxin genes and partial deletions in the tcdC gene were present in 132 isolates (84.1 percent).
  
  
  CONCLUSIONS
  A strain of C. difficile that was resistant to fluoroquinolones and had binary toxin and a partial deletion of the tcdC gene was responsible for this outbreak of C. difficile-associated diarrhea. Exposure to fluoroquinolones or cephalosporins was a risk factor.
authors.affiliation: Department of Microbiology, McGill University Health Center, Montreal, Que., Canada. vivian.loo@muhc.mcgill.ca
authors.forename: Vivian G
authors.initials: VG
authors.lastname: Loo
authors.forename: Louise
authors.initials: L
authors.lastname: Poirier
authors.forename: Mark A
authors.initials: MA
authors.lastname: Miller
authors.forename: Matthew
authors.initials: M
authors.lastname: Oughton
authors.forename: Michael D
authors.initials: MD
authors.lastname: Libman
authors.forename: Sophie
authors.initials: S
authors.lastname: Michaud
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Bourgault
authors.forename: Tuyen
authors.initials: T
authors.lastname: Nguyen
authors.forename: Charles
authors.initials: C
authors.lastname: Frenette
authors.forename: Mirabelle
authors.initials: M
authors.lastname: Kelly
authors.forename: Anne
authors.initials: A
authors.lastname: Vibien
authors.forename: Paul
authors.initials: P
authors.lastname: Brassard
authors.forename: Susan
authors.initials: S
authors.lastname: Fenn
authors.forename: Ken
authors.initials: K
authors.lastname: Dewar
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hudson
authors.forename: Ruth
authors.initials: R
authors.lastname: Horn
authors.forename: Pierre
authors.initials: P
authors.lastname: René
authors.forename: Yury
authors.initials: Y
authors.lastname: Monczak
authors.forename: André
authors.initials: A
authors.lastname: Dascal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics; D016022:Case-Control Studies; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D003015:Clostridium Infections / Q000453:epidemiology / Q000382:microbiology* / Q000401:mortality; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D005260:Female; D024841:Fluoroquinolones / Q000627:therapeutic use; D017353:Gene Deletion; D006801:Humans; D015994:Incidence; D008297:Male; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D012097:Repressor Proteins / Q000235:genetics*; D012307:Risk Factors
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D024841:Fluoroquinolones; D012097:Repressor Proteins; C105615:TcdC protein, Clostridium difficile