Genomic Signature of Multi-Drug Resistant Salmonella Typhi related to a Massive Outbreak in Zambia during 2010 - 2012.. Resistant Salmonella Typhi in Zambia

Retrospectively, we investigated the epidemiology of a massive Salmonella enterica serovar Typhi outbreak in Zambia during 2010 to 2012. Ninety-four isolates were susceptibility tested by MIC determinations. Whole genome sequence typing (WGST) of 33 isolates and bioinformatic analysis identified the MLST, haplotype, plasmid replicon, antimicrobial resistance genes, and the genetic relatedness by Single Nucleotide Polymorphism (SNP) analysis and genomic deletions. The outbreak affected 2,040 patients with a fatality rate of 0.5%. Most isolates (83.0%) were multi-drug resistant (MDR). The isolates belonged to MLST ST1 and a new variant of the haplotype; H58B. Most isolates contained a chromosomally translocate region containing seven antimicrobial resistance genes; catA1, blaTEM-1, dfrA7, sul1, sul 2, strA, and strB, fragments of incQ1plasmid replicon, class 1 integron, and the mer operon. The genomic analysis revealed an overall 415 SNPs difference and 35 deletions among 32 of the isolates whole genome sequenced. In comparison with other genomes of H58, the Zambian isolates separated from genomes from Central Africa and India with 34 and 52 SNPs, respectively.