Emergence of sulphonamide resistance in azithromycin-resistant pediatric strains of Salmonella Typhi and Paratyphi A: A genomics insight.

Whole genome sequences of Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) and Salmonella enterica subspecies enterica serovar Paratyphi A (S. Paratyphi A) from pediatric settings were used to assess the emerging Antimicrobial Resistance (AMR). The high throughput sequences of twenty pediatric clinical isolates of S. Typhi and S. Paratyphi A were retrieved and were screened for prevalent Antimicrobial Resistance Genes (ARGs) and Virulent Factors (VF). The resistance data was compared with the reference strains of S. Typhi and S. Paratyphi A. AMR studies identified sul1, sul2, dfrA7, tem-1, AH(6)-Id and APH(3″)-Ib as common ARGs. VFs were identified to understand the level of pathogenicity. The most prevalent AMR genes in the sequenced genomes were detected in phenotypically azithromycin-resistant S. Typhi. Correlation with the global genomes projected a trend of concurrent resistance to macrolides, β lactams, fluoroquinolones (FQs), tetracyclines, ansamycins, and aminoglycosides. Traces of sulphonamide-resistance were observed indicating the emergence of a currently non-prevalent S. Typhi resistance that could be a future threat. Hence new antibiotic regimen to treat azithromycin-resistant S. Typhi should be formulated by avoiding the risks of aggravating sulphonamide resistance. The identified ARGs in genomes from paediatric isolates will aid future studies to design anti-bacterial compounds against S. Typhi and S. Paratyphi A.