Salmonella serovar Infantis REPJFX01 isolates bear a pESI plasmid that includes additional genes not found in closely related non-REP strains

Abstract

Salmonella enterica subsp. enterica serovar Infantis (S. Infantis) REPJFX01 is a multidrug-resistant strain associated with poultry and international travel; this strain has been designated as a reoccurring, emerging and persistent (REP) strain by the US Centers for Disease Control and Prevention due to its identification in a number of foodborne illnesses and outbreaks. We compared publicly available S. Infantis REPJFX01 genomes to genomes of non-US isolates from the same NCBI SNP cluster and non-REP S. Infantis isolates from four other SNP clusters. When compared to isolates from the non-REP group, 135 genes were identified to be significantly (P<0.001) associated with REPJFX01; 50 of these genes were located on plasmid of emerging S. Infantis. Of the 135 REP-associated genes, 29 genes were functionally annotated and included transcription, recombination, arsenic and antimicrobial resistance genes. This suggests that the acquisition of mobile elements containing resistance genes may have favoured the emergence and spread of REPJFX01. Our results show that REPJFX01 is distributed in both North and South America, indicating that international perspectives on REP strains may be valuable.