Genome-wide analysis provides a deeper understanding of the population structure of the Salmonella enterica serotype Paratyphi B complex in Bangladesh.

Sadia Isfat Ara Rahman,Gordon Dougan,Farhana Khanam,Zoe A Dyson,Gal Horesh,Ashraful Islam Khan,Alyce Taylor-Brown,Yasmin Ara Begum,Nicholas R Thomson,Emran Kabir Chowdhury,Firdausi Qadri

doi:10.1099/mgen.0.000617

Abstract

The Salmonella enterica serotype Paratyphi B complex causes a wide range of diseases, from gastroenteritis to paratyphoid fever, depending on the biotypes Java and sensu stricto. The burden of Paratyphi B biotypes in Bangladesh is still unknown, as these are indistinguishable by Salmonella serotyping. Here, we conducted the first whole-genome sequencing (WGS) study on 79 Salmonella isolates serotyped as Paratyphi B that were collected from 10 nationwide enteric disease surveillance sites in Bangladesh. Placing these in a global genetic context revealed that these are biotype Java, and the addition of these genomes expanded the previously described PG4 clade containing Bangladeshi and UK isolates. Importantly, antimicrobial resistance (AMR) genes were scarce amongst Bangladeshi S. Java isolates, somewhat surprisingly given the widespread availability of antibiotics without prescription. This genomic information provides important insights into the significance of S. Paratyphi B biotypes in enteric disease and their implications for public health.

Highlights

The genus Salmonella, which belongs to the family Enterobacteriaceae, is commonly associated with bacterial foodborne illness in developed countries
We explored the distribution of virulence factors (VFs) throughout the Bangladeshi S
Paratyphi B is a source of confusion as biotype sensu stricto is a cause of invasive paratyphoid fever, while biotype Java is associated with non-invasive gastroenteritis

Summary

Introduction

The genus Salmonella, which belongs to the family Enterobacteriaceae, is commonly associated with bacterial foodborne illness in developed countries. Paratyphi B complex) causes both potentially life-threatening invasive paratyphoid fever and non-invasive gastroenteritis; both typhoidal and non-typhoidal types share the same somatic O antigen formula (1,4,[5],12 with the b:1,2-type of flagellar H antigen) [2], resulting in a point of confusion for microbiologists. This serotype has been further subdivided into two biotypes based on the ability to ferment dextrorotatory tartrate (dTa) and to form a slime. Paratyphi B complex [2,3,4]

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