July 7, 2019  |  

Microevolution of monophasic Salmonella Typhimurium during epidemic, United Kingdom, 2005-2010.

Authors: Petrovska, Liljana and Mather, Alison E and AbuOun, Manal and Branchu, Priscilla and Harris, Simon R and Connor, Thomas and Hopkins, K L and Underwood, A and Lettini, Antonia A and Page, Andrew and Bagnall, Mary and Wain, John and Parkhill, Julian and Dougan, Gordon and Davies, Robert and Kingsley, Robert A

Microevolution associated with emergence and expansion of new epidemic clones of bacterial pathogens holds the key to epidemiologic success. To determine microevolution associated with monophasic Salmonella Typhimurium during an epidemic, we performed comparative whole-genome sequencing and phylogenomic analysis of isolates from the United Kingdom and Italy during 2005-2012. These isolates formed a single clade distinct from recent monophasic epidemic clones previously described from North America and Spain. The UK monophasic epidemic clones showed a novel genomic island encoding resistance to heavy metals and a composite transposon encoding antimicrobial drug resistance genes not present in other Salmonella Typhimurium isolates, which may have contributed to epidemiologic success. A remarkable amount of genotypic variation accumulated during clonal expansion that occurred during the epidemic, including multiple independent acquisitions of a novel prophage carrying the sopE gene and multiple deletion events affecting the phase II flagellin locus. This high level of microevolution may affect antigenicity, pathogenicity, and transmission.

Journal: Emerging infectious diseases
DOI: 10.3201/eid2204.150531
Year: 2016

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