Genomic surveillance of Salmonella enterica serotype Minnesota strains from poultry products imported into South Africa

Salmonella enterica subspecies enterica serotype Minnesota (S. Minnesota) has recently emerged as a predominant serotype in poultry farming operations. Genomic surveillance efforts concentrated primarily in Europe have been used to evaluate food safety risks associated with S. Minnesota in imported poultry/poultry products. However, the burden imposed by S. Minnesota on consumers in sub-Saharan Africa is not understood. Here, we used whole-genome sequencing to characterize 36 S. Minnesota strains from raw poultry imported into South Africa, specifically (i) 11 strains isolated at port of entry and (ii) 25 strains from imported poultry in South African supermarkets. While all 36 strains belonged to the same sequence type (ST548), multiple ST548 lineages were present among poultry products. Comparison of the 36 strains sequenced here to all publicly available, high-quality ST548 genomes (n=460, from Enterobase) identified several public genomes differing by <30 core SNPs, including strains isolated previously from South American poultry imported into the UK. Notably, a cluster consisting of 14 highly similar genomes sequenced here (0 core SNPs) uniquely possessed bla_CTX-M-8. A search of plasmids in public databases, alongside antimicrobial resistance (AMR) genes from >1.9 million bacterial genomes, revealed that this cluster harboured bla_CTX-M-8 on an IncI1 plasmid-like region, which we hypothesize was acquired recently, from Escherichia coli. Overall, our study provides insight into the intercontinental dissemination of S. Minnesota and its associated AMR determinants via the global poultry trade.