Platelet-activating factor concentration in the stool of human newborns: effects of enteral feeding and neonatal necrotizing enterocolitis.

Epidemiologic studies have identified enteral feedings as a risk factor for necrotizing enterocolitis (NEC). Enteral feedings provide the substrate for colonization of the newborn gut with gram-negative bacteria with endotoxin production, which may trigger the production of endogenous inflammatory mediators, including platelet-activating factor (PAF). In this prospective study, we examined the effect of enteral feeding on PAF concentration in the stool of preterm and full-term human newborns. The concentration of PAF levels in stool was measured at the following times: at passage of first meconium, within 24 h prior to the onset of feedings, at the 3rd and 14th day of feeding and at any time confirmed NEC developed. Stool samples also were analyzed for levels of acetylhydrolase, the PAF breakdown enzyme. Stool PAF concentration rose significantly following the start of enteral feedings. The mean PAF concentration for day 14 samples was significantly higher than the mean concentration of meconium samples (4.90 +/- 1.03 vs. 1.81 +/- 0.38 ng/g, p < 0.05) and day 0 samples (4.90 +/- 1.03 vs. 1.79 +/- 0.39 ng/g, p < 0.05). For the 7 patients diagnosed with definite NEC, the mean stool PAF concentration was 12.42 +/- 0.77 ng/g, significantly elevated compared to the mean PAF levels in stool from healthy infants at all sampling times (p < 0.01). There was no significant change in acetylhydrolase activity at any of the sampling times. Stool PAF concentration increases with the provision of enteral feedings and rises further with the development of NEC. Since stool acetylhydrolase activity remained unchanged, we speculate the increase of PAF in stool likely represents increased PAF production at the local level following the provision of enteral feedings or the development of neonatal necrotizing enterocolitis.