Comparative genomics between Colombian clinical isolates of Monophasic Variant Salmonella Typhimurium and international clonal lineages

In Colombia, Salmonella Typhimurium monophasic variant (MVST) is the fourth serovar recovered in laboratory surveillance of acute diarrheal disease (ADD). Given its rapid worldwide dissemination, increasing multidrug-resistance, and the emergence of different endemic clones, it is considered an emerging public health problem. This study compared 21 Colombian clinical isolates and 27 MVST genomes from Europe, Asia, the United States, and Australia to know the gene pool and to define similarities with international clones. Eighty percent of the Colombian MVST isolates formed a lineage divided into 2 clones, while 4 genomes were associated with the European ST34 and USA lineages. These two Colombian clones emerged in relatively recent events, in which possible spread was established during 2011 and 2012, exhibiting a diversity of plasmids and prophages, adapting to the Colombian population after differentiation. These results are a clear example of the high plasticity of MVST, evidencing the need for active genomic surveillance to monitor the circulation of new clonal lineages.