title: An outbreak of necrotizing enterocolitis associated with norovirus genotype GII.3.
abstract: BACKGROUND
  Necrotizing enterocolitis (NEC) is an acute abdominal emergency of unknown etiology predominantly affecting preterm infants. We describe a cluster of NEC in a level III NICU involving 15 infants over a6-month period. Cohorting and stringent infection control measures were associated with termination of the cluster. A case-control study was used to investigate potential risk factors associated with development of NEC.
  
  
  METHODS
  Stool samples were collected from 55 infants (10 of 15 NEC and 45 non-NEC controls). Enteric pathogens were identified by culture and/or molecular diagnostic techniques. For the case-control study, controls were selected from admitted neonates during the same time and in the preceding 6-month period, matched for gestation and birthweight.
  
  
  RESULTS
  Forty percent (4/10) of NEC infants had norovirus RNA detected compared with 9% (4/45) of non-NEC infants (OR: 6.83, 95% CI: 1.3-34.9,P = 0.021). A lower rate of prolonged rupture of membranes and a higher rate of maternal smoking was also observed in NEC infants than in controls. No significant differences in incidences of chorioamnionitis, intrapartum antibiotics,volume of feedings, time of first formula feeding, and rates of patent ductus arteriosus or intrauterine growth retardation were detected.
  
  
  CONCLUSIONS
  Infants who developed NEC had an increased incidence of norovirus detection in their stool following diagnosis. This further strengthens the case for an etiologic role of norovirus in the pathogenesis of NEC.
authors.affiliation: Department of Infectious Diseases, Monash Medical Centre, Clayton. Victoria 3168, Australia. rhonda.stuart@southernhealth.org.au
authors.forename: Rhonda L
authors.initials: RL
authors.lastname: Stuart
authors.forename: Kenneth
authors.initials: K
authors.lastname: Tan
authors.forename: Jackie E
authors.initials: JE
authors.lastname: Mahar
authors.forename: Carl D
authors.initials: CD
authors.lastname: Kirkwood
authors.forename: C
authors.initials: C
authors.lastname: Andrew Ramsden
authors.forename: Nick
authors.initials: N
authors.lastname: Andrianopoulos
authors.forename: Damien
authors.initials: D
authors.lastname: Jolley
authors.forename: Kaye
authors.initials: K
authors.lastname: Bawden
authors.forename: Richard
authors.initials: R
authors.lastname: Doherty
authors.forename: Despina
authors.initials: D
authors.lastname: Kotsanas
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bradford
authors.forename: Jim P
authors.initials: JP
authors.lastname: Buttery
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology / Q000821:virology; D004196:Disease Outbreaks; D020345:Enterocolitis, Necrotizing / Q000453:epidemiology* / Q000821:virology*; D005243:Feces / Q000821:virology; D005260:Female; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D017053:Infection Control / Q000379:methods; D007363:Intensive Care Units, Neonatal; D008297:Male; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D012367:RNA, Viral / Q000302:isolation & purification; D012307:Risk Factors
chemical_list: D012367:RNA, Viral