Development of a real-time PCR method for the genoserotyping of Salmonella Paratyphi B variant Java

Mathieu Gand,Assia Saltykova,Katelijne Dierick,Nancy Roosens,Kathleen Marchal,Sophie Bertrand,Sigrid C J De Keersmaecker,Wesley Mattheus

doi:10.1007/s00253-019-09854-4

Mathieu Gand, Assia Saltykova + Show 6 more

Open Access

https://doi.org/10.1007/s00253-019-09854-4

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Abstract

Discriminating between d-tartrate fermenting and non-fermenting strains of Salmonella enterica subsp. enterica serotype Paratyphi B is of major importance as these two variants have different pathogenic profiles. While d-tartrate non-fermenting S. Paratyphi B isolates are the causative agent of typhoid-like fever, d-tartrate fermenting isolates (also called variant Java) of the same serotype trigger the less dangerous gastroenteritis. The determination of S. Paratyphi B variants requires a time-consuming process and complex biochemical tests. Therefore, a quadruplex real-time PCR method, based on the allelic discrimination of molecular markers selected from the scientific literature and from whole genome sequencing data produced in-house, was developed in this study, to be applied to Salmonella isolates. This method was validated with the analysis of 178 S. Paratyphi B (d-tartrate fermenting and non-fermenting) and other serotypes reaching an accuracy, compared with the classical methods, of 98% for serotyping by slide agglutination and 100% for replacement of the biochemical test. The developed real-time PCR permits to save time and to obtain an accurate identification of a S. Paratyphi B serotype and its d-tartrate fermenting profile, which is needed in routine laboratories for fast and efficient diagnostics.

Highlights

Salmonella is one of the major causes of food poisoning all over the world
We developed a multiplex real-time PCR method, based on markers found in the scientific literature and on in-house produced whole genome sequencing (WGS) results, in order to replace the dT variant biochemical test and simultaneously confirm the Paratyphi B serotype identification, once Salmonella is isolated from its matrix
While all the dT+ isolates were correctly identified by the PCR Malorny, no 384-bp fragments were detected for three (2012-45, S16BD08024, and S16BD08272) of the six S

Summary

Introduction

Salmonella is one of the major causes of food poisoning all over the world. These bacteria can contaminate a large variety of food products including those of animal origin such as eggs, milk products, or meat. This is why the combat against zoonotic Salmonella (EU regulation No. 2160/2003, Belgium FASFC advice 03-2012) is crucial to rapidly identify serotypes that may contaminate the food chain like Paratyphi B variant Java in poultry products. One of the major concerns of Salmonella is economic loss due to contaminated food destruction and economic inactivity due to sickness leave. De Keersmaecker and Sophie Bertrand contributed to this work

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