title: Asymptomatic Carriers Contribute to Nosocomial Clostridium difficile Infection: A Cohort Study of 4508 Patients.
abstract: Nosocomial infections with Clostridium difficile present a considerable problem despite numerous attempts by health care workers to reduce risk of transmission. Asymptomatic carriers of C difficile can spread their infection to other patients. We investigated the effects of asymptomatic carriers on nosocomial C difficile infections.
  
  
  
  We performed a population-based prospective cohort study at 2 university hospitals in Denmark, screening all patients for toxigenic C difficile in the intestine upon admittance, from October 1, 2012, to January 31, 2013. Screening results were blinded to patients, staff, and researchers. Patients were followed during their hospital stay by daily registration of wards and patient rooms. The primary outcomes were rate of C difficile infection in exposed and unexposed patients and factors associated with transmission.
  
  
  
  C difficile infection was detected in 2.6% of patients not exposed to carriers and in 4.6% of patients exposed to asymptomatic carriers at the ward level (odds ratio for infection if exposed to carrier, 1.79; 95% confidence interval, 1.16-2.76). Amount of exposure correlated with risk of C difficile infection, from 2.2% in the lowest quartile to 4.2% in the highest quartile of exposed patients (P = .026). Combining the load of exposure to carriers and length of stay seemed to have an additive effect on the risk of contracting C difficile.
  
  
  
  In a population-based prospective cohort study in Denmark, we found that asymptomatic carriers of toxigenic C difficile in hospitals increase risk of infection in other patients.
authors.affiliation: Department of Gastroenterology, Frederiksberg Hospital, University of Copenhagen, Frederiksberg, Denmark; Department of Gastroenterology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark. Electronic address: tns@regionsjaelland.dk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Blixt
authors.affiliation: Center for Clinical Epidemiology, South, Odense University Hospital, Odense, Denmark; Research Unit of Clinical Epidemiology, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Kim Oren
authors.initials: KO
authors.lastname: Gradel
authors.affiliation: Department of Gastroenterology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Homann
authors.affiliation: Department of Gastroenterology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Department of Gastroenterology, Herlev Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: Jakob Benedict
authors.initials: JB
authors.lastname: Seidelin
authors.affiliation: Department of Clinical Microbiology, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark; Institute for Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Schønning
authors.affiliation: Department of Clinical Microbiology, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark; Infectious Control, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Infection Control, Frederiksberg Hospitals, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Lester
authors.affiliation: Infectious Control, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Infection Control, Frederiksberg Hospitals, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Jette
authors.initials: J
authors.lastname: Houlind
authors.affiliation: Infectious Control, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Infection Control, Frederiksberg Hospitals, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Marie
authors.initials: M
authors.lastname: Stangerup
authors.affiliation: Department of Pulmonary Medicine, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Magnus
authors.initials: M
authors.lastname: Gottlieb
authors.affiliation: Department of Clinical Microbiology, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark; Infectious Control, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Infection Control, Frederiksberg Hospitals, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Jenny Dahl
authors.initials: JD
authors.lastname: Knudsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058345:Asymptomatic Infections / Q000453:epidemiology*; D002353:Carrier State / Q000175:diagnosis / Q000453:epidemiology*; D016360:Clostridioides difficile / Q000235:genetics; D003015:Clostridium Infections / Q000175:diagnosis / Q000453:epidemiology; D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology*; D003718:Denmark / Q000453:epidemiology; D004761:Enterocolitis, Pseudomembranous / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D016017:Odds Ratio; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D055815:Young Adult
keywords: Bacteria; CDI; Outbreak; Pathogen