Neonatal enteral feeding tube as loci for Enterobacteriaceae colonisation and risk to neonatal health
The incidence of neonatal infections caused by Enterobacteriaceae has been increasing in recent years, and they are now recognised as the predominant causative agents in neonatal intensive care unit (NICU) outbreaks. Klebsiella spp. and Serratia spp. are the most common causative pathogens, and E. coli is one of the leading causes of neonatal meningitis and sepsis. The infant intestinal flora is influenced by the feeding regime. This study focuses on assessing the risk to neonates from the ingestion of the Enterobacteriaceae such as; Enterobacter hormaechei, Enterobacter ludwigii, Enterobacter aerogenes, Enterobacter cloacae and Klebsiella oxytoca. The strains under study were isolated from two sources; human mastic breast milk (MBM) and neonatal nasogastric enteral feeding tubes (EFT). The overall aim was to evaluate the risk to neonates posed by the ingestion of these organisms either from contaminated breast milk or from infant formula. Due to the lack of adequate source information, it was necessary to first confirm the identity of the strains under investigation. This was achieved using standard biochemical profiles (phenotyping) and where necessary 16S rDNA sequence analysis. Secondly, it was necessary to determine whether all strains were unique or if any were multiple isolations of the same strain. This was achieved using Pulsed-Field Gel Electrophoresis (PFGE). To determine the potential exposure of neonates to these organisms, a range of physiological and virulence related assays were undertaken; heat tolerance to 55°C, biofilm formation, capsule formation and acidic pH survival (pH 3.5).