An outbreak of necrotizing enterocolitis associated with norovirus genotype GII.3.
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.
Stuart
Rhonda L
RL
Department of Infectious Diseases, Monash Medical Centre, Clayton. Victoria 3168, Australia. rhonda.stuart@southernhealth.org.au
Tan
Kenneth
K
Mahar
Jackie E
JE
Kirkwood
Carl D
CD
Andrew Ramsden
C
C
Andrianopoulos
Nick
N
Jolley
Damien
D
Bawden
Kaye
K
Doherty
Richard
R
Kotsanas
Despina
D
Bradford
Jennifer
J
Buttery
Jim P
JP
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
D012367:RNA, Viral