Contaminated milk is a common cause of necrotising enterocolitis: A hypothesis

Necrotising enterocolitis (NEC) is the most commonly acquired gastrointestinal disease of neonates, particularly the very preterm (gestation <32 weeks) and/or very low birth weight (<1500g). It is associated with high morbidity and mortality. Despite improvement in neonatal care and increased use of expressed breast milk (EBM), the incidence remains high in many neonatal intensive care units (NICU), and even shows increasing trend in some countries. Numerous studies have pointed to the infective nature of NEC. Some investigators have reported an increase in the incidence of NEC in their NICU when the percentage of infants with pathogens isolated from their gut increased, and decreased when gut colonisation rate was low. Both bacteria and viruses have been reported to be associated with outbreaks of NEC. The majority (>90%) of the NEC cases occurred in neonates on enteral feeding. Studies have shown that milk (whether EBM or formula) fed to neonates was not sterile and were further contaminated during collection, transport, storage and/or feeding. Other investigators have reported a reduction in the incidence of NEC when they improved infection control measures and hygienic procedures in handling milk. It is, therefore, hypothesised that the most common cause of NEC is due to the feeding of neonates, particularly the vulnerable very preterm small neonates, with milk heavily contaminated during collection at source, transport, storage and/or feeding. Because of the immaturity of the immune system of the neonates, excessive inflammatory response to the pathogen load in the gut leads to the pathogenesis of NEC.