title: Norovirus Genotypes in Hospital Settings: Differences Between Nosocomial and Community-Acquired Infections.
abstract: BACKGROUND
  Norovirus (NoV) is a major cause of gastroenteritis and hospital outbreaks, leading to substantial morbidity and direct healthcare expenses as well as indirect societal costs. The aim of the study was to estimate the proportion of nosocomial NoV infections among inpatients testing positive for NoV in Denmark, 2002-2010, and to study the distribution of NoV genotypes among inpatients with nosocomial and community-acquired NoV infections, respectively.
  
  
  METHODS
  Admission and stool sampling dates from 3656 NoV-infected patients were used to estimate the proportion of nosocomial infections. The associations between nosocomial infection and patient age, sex, and NoV genotype GII.4 were examined.
  
  
  RESULTS
  Of the 3656 inpatients, 63% were classified as having nosocomial infections. Among these, 9 capsid and 8 polymerase NoV genotypes were detected, whereas in the smaller group of inpatients with community-acquired infections, 12 capsid and 9 polymerase genotypes were detected. Nosocomial NoV infections were associated with age ≥60 years and infections with genotype GII.4.
  
  
  CONCLUSIONS
  The majority of NoV infections in hospitalized patients were nosocomial. Nosocomial infection was mainly associated with older age but also with the specific genotype GII.4. The genotypes in community-acquired NoV infections were more heterogeneous than in nosocomial infections.
authors.affiliation: Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen Research Unit for Clinical Microbiology, University of Southern Denmark, Odense.
authors.forename: Kristina Træholt
authors.initials: KT
authors.lastname: Franck
authors.affiliation: Department of Clinical Microbiology, Copenhagen University Hospital Herlev.
authors.forename: Rikke Thoft
authors.initials: RT
authors.lastname: Nielsen
authors.affiliation: Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen.
authors.forename: Barbara Juliane
authors.initials: BJ
authors.lastname: Holzknecht
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.
authors.forename: Annette Kjær
authors.initials: AK
authors.lastname: Ersbøll
authors.affiliation: Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen.
authors.forename: Thea Kølsen
authors.initials: TK
authors.lastname: Fischer
authors.affiliation: Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen Department of Laboratory Medicine Malmö, Lund University, Sweden.
authors.forename: Blenda
authors.initials: B
authors.lastname: Böttiger
mesh_terms: D000293:Adolescent; D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology / Q000821:virology*; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000821:virology*; D003428:Cross Infection / Q000453:epidemiology / Q000821:virology*; D003718:Denmark / Q000453:epidemiology; D005243:Feces / Q000821:virology; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D029322:Norovirus / Q000145:classification / Q000235:genetics*; D055815:Young Adult
keywords: Caliciviridae; community-acquired; gastroenteritis; genetic diversity; genotypes; healthcare; healthcare-associated infection; hospitals; norovirus; nosocomial