Background Nowadays, hospitals foment breastfeeding or human donor milk to provide the best feeding option to the preterm infant. This fact may represent a key factor in the initiation and development of the infant gut microbiota.
Aims To analyse the bacterial diversity in meconium and feces of preterm neonates and to evaluate the impact of the nasogastric enteral feeding tubes and the feeding option in its evolution.
Method 26 mother/preterm neonates (< 32 weeks gestation) pairs participated in the study providing a sample of colostrum/breast milk and meconium/feces. Milk samples were obtained after their pass through the nasogastric feeding tubes. Samples were plated onto different culture media. The isolates were identified by PCR sequencing. Scanning electron microscopy (SEM) was used to observe biofilm formation on the feeding tubes.
Results Approximately 4,000 isolates were identified. The dominant genera in both samples were Staphylococcus, Enterococcus, Serratia, Klebsiella and Escherichia. They were present at high concentrations independently of the feeding option. Lactobacilli and bifidobacteria were detected in a low percentage of the samples. Analysis of several parts of the nasogastric tubes by SEM revealed the presence of a dense bacterial biofilm. Biofilms were composed of the same bacterial groups that dominated in the fecal and milk/formula samples.
Conclusions There is a direct relationship between the high bacterial concentrations found in the biological samples and the biofilm formed in the nasogastric tubes. Fecal microbiota of preterm neonates are strongly influenced by those species highly prevalent the hospitalary environment.