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Characterizing the pathotype of neonatal meningitis causing Escherichia coli (NMEC)

Wijetunge, D. S. S.; Gongati, S. ; DebRoy, C. ; Kim, K. S. ; Couraud, P. O. ; Romero, I. A.; Weksler, B. and Kariyawasam, S. (2015). Characterizing the pathotype of neonatal meningitis causing Escherichia coli (NMEC). BMC Microbiology, 15, article no. 211.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1186/s12866-015-0547-9
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Abstract

Background Neonatal meningitis-causing Escherichia coli (NMEC) is the predominant Gram-negative bacterial pathogen associated with meningitis in newborn infants. High levels of heterogeneity and diversity have been observed in the repertoire of virulence traits and other characteristics among strains of NMEC making it difficult to define the NMEC pathotype. The objective of the present study was to identify genotypic and phenotypic characteristics of NMEC that can be used to distinguish them from commensal E. coli.
Methods A total of 53 isolates of NMEC obtained from neonates with meningitis and 48 isolates of fecal E. coli obtained from healthy individuals (HFEC) were comparatively evaluated using five phenotypic (serotyping, serum bactericidal assay, biofilm assay, antimicorbial susceptibility testing, and in vitro cell invasion assay) and three genotypic (phylogrouping, virulence genotyping, and pulsed-field gel electrophoresis) methods.
Results A majority (67.92 %) of NMEC belonged to B2 phylogenetic group whereas 59 % of HFEC belonged to groups A and D. Serotyping revealed that the most common O and H types present in NMEC tested were O1 (15 %), O8 (11.3 %), O18 (13.2 %), and H7 (25.3 %). In contrast, none of the HFEC tested belonged to O1 or O18 serogroups. The most common serogroup identified in HFEC was O8 (6.25 %). The virulence genotyping reflected that more than 70 % of NMEC carried kpsII, K1, neuC, iucC, sitA, and vat genes with only less than 27 % of HFEC possessing these genes. All NMEC and 79 % of HFEC tested were able to invade human cerebral microvascular endothelial cells. No statistically significant difference was observed in the serum resistance phenotype between NMEC and HFEC. The NMEC strains demonstrated a greater ability to form biofilms in Luria Bertani broth medium than did HFEC (79.2 % vs 39.9 %).
Conclusion The results of our study demonstrated that virulence genotyping and phylogrouping may assist in defining the potential NMEC pathotype.

Item Type: Journal Item
Copyright Holders: 2015 The Authors
ISSN: 1471-2180
Extra Information: 15 pp.
Keywords: biofilms; Escherichia coli; genotyping; invasion assay; neonatal meningitis; serotyping; virulence
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Life, Health and Chemical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Interdisciplinary Research Centre: Biomedical Research Network (BRN)
Item ID: 44661
Depositing User: Ignacio A Romero
Date Deposited: 22 Oct 2015 10:27
Last Modified: 22 Nov 2016 18:04
URI: http://oro.open.ac.uk/id/eprint/44661
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