Comparative genomic analysis provides new insights into non-typhoidal Salmonella population structure in Peru.

Non-typhoidal Salmonella (NTS) is one of the leading causes of foodborne outbreaks worldwide, especially in low- and middle-income countries such as Peru. To understand the dynamics of NTS serotypes circulating in the country, the whole genomes of 1122 NTS strains from 1998 to 2018 were analyzed using phylogenomic and comparative genomics tools. A total of 40 different Sequences Type (STs) were identified, the five most frequent being ST-32 (S. Infantis, 37.25%), ST-11 (S. Enteritidis, 23.8%), ST-19 (S. Typhimurium, 14.17%), ST-31 (S. Newport, 6.77%), and ST-413 (S. Mbandaka, 4.72%). Furthermore, the maximum likelihood phylogeny showed high clonality between strains from the same ST recovered from different isolation sources, as well as a variable recombination rate, when comparing each ST individually. Moreover, several virulence factors involved in adherence and invasion, as well as plasmids and prophages, are strongly associated with the most frequent STs, while multidrug resistance markers are mostly linked to ST-32. This work provides an overview of the main genomic characteristics linked to the high-frequency ST, which have undergone few genetic modifications over time, suggesting a high adaptation of these NTS circulating clones in Peru.