Profiling potentially pathogenic bacteria from neonatal feeding tubes and sepsis cases

Dahmani, K.A., 2018. Profiling potentially pathogenic bacteria from neonatal feeding tubes and sepsis cases. PhD, Nottingham Trent University.

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Abstract

Recently, there has been a rise in the incidence of neonatal infections among babies born with low birth-weights and under-developed immune systems in neonatal intensive care units (NICUs). There are several risk factors to neonatal infection, the most important of which include the use of medical devices such as nasogastric enteral feeding tubes (NEFTs) and through contamination of infant feeding formula. Therefore, bacterial analysis of feeding tubes used in the NICU is important to identify infection risk factors during neonatal enteral feeding.

The aims of this study were (a) to determine the potential risk to neonates posed by ingestion of A. baumannii and Enterobacter spp., in particular E. hormaechei either through feeding tubes, infant formula, or by contaminated milk, (b) to determine whether some of the isolated strains originate from common sources, such as being transferred between the babies within specific neonatal units. Additionally, a longitudinal study for premature twin babies aimed to compare potentially pathogenic E. faecium isolates within and between the feeding tubes and faeces of twin babies over time.

PFGE indicated that all of the A. baumannii strains formed two different STs (ST193 and ST113). All ST113 strains were multidrug-resistant and demonstrated an ability to form significant biofilms at 37 °C in infant formula. Tolerance of acidic conditions, desiccation, resistance to human serum and persistence inside macrophages were shown by the majority of strains tested. E. hormaechei strains from feeding tubes exhibited similar behaviour to those isolated from sepsis cases, since both were able to adhere to and invade Caco-2 and HBMEC cell lines. Also, these strains were able to persist and replicate inside macrophages for up to 72 hours.

In the longitudinal study, all isolates of E. faecium isolated from preterm infant twins during their hospitalisation in the NICU were typed as ST80, belonging to clonal complex CC17. Furthermore, they were resistant to ampicillin and were found to carry several virulence-associated genes such as esp. All of these strains were found to be essentially the same strain based on their sequence type and genomic analysis and were shown to have high pathogenic potential. These strains isolated from different neonatal locations were indeed the same clone, showing that the bacteria were able to persist and be transferred between the two premature infants in the NICU.

This study has provided evidence of colonisation and persistence of opportunistic ESKAPE group pathogens in neonatal feeding tubes, which are important causes of nosocomial infection and dissemination of multidrug-resistant (MDR) strains.

Item Type: Thesis
Description: Abridged version.
Creators: Dahmani, K.A.
Date: December 2018
Rights: I hereby certify that the work presented herein is the result of my own research work, except where reference has been made to published literature. I have composed the thesis and the work has not been submitted for any other degree or professional qualification. All the work was conducted in the School of Science and Technology at the Nottingham Trent University. You may copy up to 5% of this work for the private study or personal, non-commercial research. Any information used from this thesis should be fully cited.
Divisions: Schools > School of Science and Technology
Depositing User: Jill Tomkinson
Date Added: 31 Oct 2019 11:58
Last Modified: 21 Nov 2019 09:15
URI: http://irep.ntu.ac.uk/id/eprint/38086

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