|Luo, Yan - U.s. Food & Drug Administration (FDA)|
|Allard, Marc - U.s. Food & Drug Administration (FDA)|
|Brown, Eric - U.s. Food & Drug Administration (FDA)|
|Van Kessel, Jo Ann|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/9/2014
Publication Date: 4/23/2014
Citation: Haley, B.J., Luo, Y., Allard, M., Brown, E., Karns, J.S., Van Kessel, J.S. 2014. Evolution of Salmonella Cerro on a dairy farm over an eight-year period. BARC Poster Day.
Technical Abstract: Salmonella enterica subsp. enterica serovar Cerro, frequently isolated from dairy cattle and an occasional pathogen of humans, was recurrently isolated over an eight-year period on a dairy farm in south-central Pennsylvania. The genomes of 18 S. Cerro isolates recovered directly from the feces of individual animals were sequenced using large-scale pyrosequencing technology. Phylogenetic inference demonstrated that two clades of S. Cerro radiating from a common ancestor were present on the farm at different times. Strains within one clade were isolated during the initial period of the epidemic (2005 to 2008) and strains isolated during a later period of the epidemic fell within a second clade (2009 to 2012). Extinction of S. Cerro isolates from the earlier clade coincided with an increase in S. Kentucky prevalence within the herd while isolation rates of the second clade paralleled those of S. Kentucky. When isolated S. Cerro genomes were compared within each clade and between clades, heterogeneity with respect to gene content and SNPs was relatively low, but apparent, demonstrating that the Salmonella genomes were not static over the course of the outbreak, and that diversification occurred over time.