Bifidobacterial supplementation reduces the incidence of necrotizing enterocolitis in a neonatal rat model

Background Br Aims: Neonatal necrotizing enterocolitis (NEC) is a devastati ng gastrointestinal disease of premature infants partly caused by intestina l bacterial proliferation. Because bifidobacteria are thought to reduce the risk for intestinal disturbances associated with pathogenic bacterial colo nization, we hypothesized that exogenous bifidobacterial supplementation to newborn rats would result in intestinal colonization and a reduction in th e incidence of neonatal NEC. Methods: Newborn rat pups were given Bifidobac terium infantis (10(9) organisms per animal daily), Escherichia coil, or sa line control and exposed to the NEC protocol consisting of formula feeding (Esbilac; 200 cal.kg(-1).day(-1)) and asphyxia (100% N-2 for 50 seconds fol lowed by cold exposure for 10 minutes). Outcome measures included stool and intestinal microbiological evaluation, gross and histological evidence of NEC, plasma endotoxin concentration, intestinal phospholipase A(2) expressi on, and estimation of intestinal mucosal permeability. Results: Bifidobacte rial supplementation resulted in intestinal colonization by 24 hours and ap pearance in stool samples by 48 hours. Bifidobacteria-supplemented animals had a significant reduction in the incidence of NEC compared with controls and E. coli-treated animals (NEC, 7/24 B. infantis vs. 19/27 control vs. 16 /23 E. coli,. P < 0.01). Plasma endotoxin and intestinal phospholipase A(2) expression were lower in bifidobacteria-treated pups than in controls, sup porting the role of bacterial translocation and activation of the inflammat ory cascade in the pathophysiology of NEC. Conclusions: Intestinal bifidoba cterial colonization reduces the risk of NEC in newborn rats.