First-Pass Meconium Samples from Healthy Term Vaginally-Delivered Neonates: An Analysis of the Microbiota

Considerable effort has been made to categorise the bacterial composition of the human gut and correlate findings with gastrointestinal disease. The infant gut has long been considered sterile at birth followed by rapid colonisation; however, this view has recently been challenged. We examined first-pass meconium from healthy term infants to confirm or refute sterility.. Absolute counts of all bacteria and proportional identification of each bacterial group were calculated. Confirmation of bacterial presence by PCR was undertaken on FISH-positive samples. the most prevalent. There was no association between bacterial counts and rupture of membrane duration, time to passage of meconium or time to lab.This study provides evidence that low numbers of bacteria are present in first-pass meconium samples from healthy, vaginally-delivered, breastfed term infants. Only two-thirds of meconium samples had detectable bacteria, though at levels too low for automated counting or for reliable confirmation by PCR. This study suggests that gut bacterial colonisation is extremely limited at birth and occurs rapidly thereafter