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Title: Virulence potential of Enterobacteriaceae isolated from neonatal enternal feeding tubes
Author: Alkeskas, A. A.
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2013
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In recent years, there has been a rise in the incidence of neonatal infections due to Enterobacteriaceae including Escherichia coli, Enterobacter, Klebsiella and Serratia spp. These are major causative agents in neonatal intensive care unit (NICU) infections. Neonates, especially those born with low birth weight (< 2000g), are fed via a nasogastric tube. Despite recent concerns over the microbiological safety of infant feeds, there has been no consideration that the nasogastric enteral feeding tube may act as a site for bacterial colonisation and act as a locus for infection. Therefore bacterial analysis of used feeding tubes is of importance with regard to identifying risk factors during neonatal enteral feeding. The aims of this study were to determine whether neonatal nasogastric enteral feeding tubes are colonised by opportunistic pathogens in the Enterobacteriaceae, and whether their presence was influenced by the feeding regime. In this research a collection 224 Enterobacteriaceae strains previously isolated from the enteral feeding tubes of neonates on intensive care units have been analysed. This study describes the use of DNA finger printing, via pulsed-field gel electrophoresis (PFGE), to determine if the same strains were isolated on different occasions from the NICUs. Therefore indicating whether certain strains have colonised the NICUs leading to increased exposure and risk to the neonates. The second project aim compared the virulence potential of Enterobacteriaceae, many of which were associated with feeding tubes. Twenty strains were chosen that represented species from the major genera isolated; E. coli, Serratia, Klebsiella and Enterobacter spp. Virulence to mammalian cells has been assessed using attachment and invasion studies of human colonic carcinoma epithelial cells (Caco-2), rat blood brain barrier cells (rBECE4) and human brain microvascular endothelial cells (HBMEC) tissue culture cells. Macrophage survival was studied using the (U937) cell line of human monocyte cells. The analysis has covered attachment and invasion of human intestinal cells, survival in macrophages, and invasion of rat and human brain cells. The results show that certain strains of E. coli k1 isolated from neonatal feeding tubes are able to persist in macrophages and hence be dispersed and potentially cause systemic infections.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available