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

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.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Nottingham Trent University

Year dc:date.issued

2013

Author dc:creator

• Joseph, SM

Language dc:language

en