Whole-genome sequencing of extensively drug-resistant Salmonella enterica serovar Typhi clinical isolates from the Peshawar region of Pakistan.

BACKGROUND: Typhoid fever, caused by Salmonella enterica serovar Typhi, is a significant public health concern due to the escalating of antimicrobial resistance (AMR), with limited treatment options for extensively drug-resistant (XDR) S. Typhi strains pose a serious threat to disease management and control. This study aimed to investigate the genomic characteristics, epidemiology and AMR genes of XDR S. Typhi strains from typhoid fever patients in Pakistan. METHODOLOGY: We assessed 200 patients with enteric fever symptoms, confirming 65 S. Typhi cases through culturing and biochemical tests. Subsequent antimicrobial susceptibility testing revealed 40 cases of extensively drug-resistant (XDR) and 25 cases of multi-drug resistance (MDR). Thirteen XDR strains were selected for whole-genome sequencing, to analyze their sequence type, phylogenetics, resistance genes, pathogenicity islands, and plasmid sequences using variety of data analysis resources. Pangenome analysis was conducted for 140 XDR strains, including thirteen in-house and 127 strains reported from other regions of Pakistan, to assess their genetic diversity and functional annotation. RESULTS: MLST analysis classified all isolates as sequence type 1 (ST-1) with 4.3.1.1. P1 genotype characterization. Prophage and Salmonella Pathogenicity Island (SPI) analysis identified intact prophages and eight SPIs involved in Salmonella's invasion and replication within host cells. Genome data analysis revealed numerous AMR genes including dfrA7, sul1, qnrS1, TEM-1, Cat1, and CTX-M-15, and SNPs associated with antibiotics resistance. IncY, IncQ1, pMAC, and pAbTS2 plasmids, conferring antimicrobial resistance, were detected in a few XDR S. Typhi strains. Phylogenetic analysis inferred a close epidemiological linkage among XDR strains from different regions of Pakistan. Pangenome was noted closed among these strains and functional annotation highlighted genes related to metabolism and pathogenesis. CONCLUSION: This study revealed a uniform genotypic background among XDR S. Typhi strains in Pakistan, signifying a persistence transmission of a single, highly antibiotic-resistant clone. The closed pan-genome observed underscores limited genetic diversity and highlights the importance of genomic surveillance for combating drug-resistant typhoid infections.

The genetic composition of Shina population from Gilgit-Baltistan, Pakistan based on mtDNA analyses.

The present study aimed to gain insight into the genetic origin of the Shina population from Gilgit-Baltistan, Pakistan. We partially performed the mitochondrial DNA (mtDNA) control region of healthy unrelated individuals of Shina tribe residing in the remote area of Gilgit-Baltistan to investigate their maternal lineages. The present study is the first report about Shina's genetic structure, origin, and relationship with the surrounding north-western Pakistani population. The mtDNA sequences of the Shina samples were compared with the revised Cambridge Reference Sequence (rCRS) and the HVR-1 D-loop region was covered. The comparison with rCRS identified overall 38 haplotypes and 08 haplogroups for Shina samples. Among these haplotypes, 18 were shared by more than one individual of the Shina tribe. The obtained mtDNA sequences of Shina were compared with surrounding north-western Pakistani population groups, i.e. Kho, Kashmiri, and Pathan. The genetic diversity (i.e. 1.0424) and power of discrimination (i.e. 0.9266) of the Shina was found equivalent to surrounding north-western groups. The haplogroups frequencies, phylogenetic tree and network analysis identified the west Eurasian ancestral origin of Shina group with nearby maternal ancestral relationships with the Kashmiri population. However, no close genetic relationship of Shina was depicted with nearby residing Kho population group.