Diversity and virulence of the genus Cronobacter revealed by multilocus sequence typing (MLST) and comparative genomic analysis

JOSEPH, S.M., 2013. Diversity and virulence of the genus Cronobacter revealed by multilocus sequence typing (MLST) and comparative genomic analysis. PhD, Nottingham Trent University.

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Abstract

Cronobacter spp. (previously known as Enterobacter sakazakii) is a diverse bacterial genus consisting of opportunistic food-borne pathogens affecting all age groups, with particularly severe clinical complications such as meningitis and necrotising enterocolitis in neonates and infants. In this study, a multilocus sequence typing (MLST) approach has been established to span the entire Cronobacter genus, by employing the alleles of 7 housekeeping genes (atpD, fusA, glnS, gltB, gyrB, infB and ppsA, total length 3036 bp). The 325 Cronobacter spp. strains used in the study included isolates from the highly publicised Cronobacter cases from USA in December 2011. The scheme identified 115 sequence types (ST) across the seven Cronobacter species. Multilocus sequence analysis (MLSA) revealed considerable diversity in the genus, with intraspecific variation ranging from low diversity in C. sakazakii to extensive diversity within some species such as C. muytjensii and C. dublinensis including evidence of recombination events between species. An evolutionary analysis revealed the Cronobacter genus to have evolved 45-68 million years ago, during the period of evolution of flowering plants. The MLSA was also used in a polyphasic study for the formal recognition of two new species – C. universalis and C. condimenti. The MLST scheme also revealed the high level of clonality in the species C. sakazakii and C. malonaticus. ST4 was found to be a highly stable clone of C. sakazakii, and a strong association was established between the C. sakazakii ST4 clonal complex with neonatal meningitis cases.

Item Type: Thesis
Creators: Joseph, S.M.
Date: 2013
Rights: Experimental work contained in this thesis is original research carried out by the author, unless otherwise stated, in the School of Science and Technology at the Nottingham Trent University. No material contained herein has been submitted for any other degree, or at any other institution. This work is the intellectual property of the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the owner(s) of the Intellectual Property Rights.
Divisions: Schools > School of Science and Technology
Depositing User: EPrints Services
Date Added: 09 Oct 2015 09:35
Last Modified: 09 Oct 2015 09:35
URI: http://irep.ntu.ac.uk/id/eprint/221

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