Colonization of the gut with Gram-negative bacilli, its association with neonatal sepsis and its clinical relevance in a developing country

Abstract

This study examined the pattern of colonization of the neonatal gut by aerobic Gram-negative bacilli (GNB) and evaluated the association between gut colonization and sepsis in the developing world. This deserves attention because of the high incidence of sepsis and the differences in hygienic environments in developing countries compared with the developed world. The study was carried out on neonates in a tertiary-care government hospital. Serial gut samples were analysed (gastric aspirates and stool samples) for GNB. Blood samples of cases showing clinical signs of sepsis were also analysed for septic screening and culture positivity. Antibiograms, serotyping and PFGE were carried out to evaluate the relatedness of the gut and blood isolates. A diverse array of GNB was isolated from the gut of the neonates, Klebsiella pneumoniae being most common, followed by Escherichia coli. The rate of isolation of GNB was consistently higher in stool samples compared with gastric aspirate samples. Colonization was influenced by a stay in the neonatal intensive care unit and by the prolonged use of a feeding tube. GNB were the cause of sepsis in the majority of cases, with K. pneumoniae being the most frequently isolated GNB from the blood. Acinetobacter baumannii, Escherichia coli, Enterobacter cloacae and Burkholderia cepacia were the other GNB recovered from the blood of the neonates. Neonates with GNB in the gut had a higher incidence of clinical sepsis than those without. In 50 % of cases, the genotypes of the organisms found in the blood were indistinguishable from their gut counterpart. These results show that the neonatal gut is colonized with a diverse array of GNB, and an association between gut colonization and neonatal sepsis was observed.