MLVA as a tool for public health surveillance of human Salmonella Typhimurium: prospective study in Belgium and evaluation of MLVA loci stability.

Véronique Wuyts,Kathleen Marchal,Guillaume De Laminne De Bex,Christa Wildemauwe,Sigrid C J De Keersmaecker,Wesley Mattheus,Nancy H C Roosens,Sophie Bertrand

doi:10.1371/journal.pone.0084055

Véronique Wuyts, Kathleen Marchal + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0084055

Copy DOI

Journal: PloS one	Publication Date: Dec 31, 2013
Citations: 42	License type: CC BY 4.0

Abstract

Surveillance of Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) is generally considered to benefit from molecular techniques like multiple-locus variable-number of tandem repeats analysis (MLVA), which allow earlier detection and confinement of outbreaks. Here, a surveillance study, including phage typing, antimicrobial susceptibility testing and the in Europe most commonly used 5-loci MLVA on 1,420 S. Typhimurium isolates collected between 2010 and 2012 in Belgium, was used to evaluate the added value of MLVA for public health surveillance. Phage types DT193, DT195, DT120, DT104, DT12 and U302 dominate the Belgian S. Typhimurium population. A combined resistance to ampicillin, streptomycin, sulphonamides and tetracycline (ASSuT) with or without additional resistances was observed for 42.5% of the isolates. 414 different MLVA profiles were detected, of which 14 frequent profiles included 44.4% of the S. Typhimurium population. During a serial passage experiment on selected isolates to investigate the in vitro stability of the 5 MLVA loci, variations over time were observed for loci STTR6, STTR10, STTR5 and STTR9. This study demonstrates that MLVA improves public health surveillance of S. Typhimurium. However, the 5-loci MLVA should be complemented with other subtyping methods for investigation of possible outbreaks with frequent MLVA profiles. Also, variability in these MLVA loci should be taken into account when investigating extended outbreaks and studying dynamics over longer periods.

Highlights

Salmonella is the most frequent cause of food-borne outbreaks and human salmonellosis is the second most frequently reported zoonosis in the European Union [1]
Phage typing as a subtyping technique is often complemented with molecular methods like pulsed-field gel electrophoresis (PFGE), which is considered the gold standard for subtyping of Salmonella [2]
Typhimurium is the most frequently isolated serovar from human patients in Belgium and subtyping of this serovar is very important for outbreak detection and tracing outbreak sources

Summary

Introduction

Salmonella is the most frequent cause of food-borne outbreaks and human salmonellosis is the second most frequently reported zoonosis in the European Union [1]. The most common serovars of Salmonella isolated from human outbreaks are Salmonella enterica subsp. Typing methods which allow characterization below the serovar level are essential in a surveillance program for this diverse genus. Classical surveillance programs for Salmonella rely on phenotyping methods such as phage typing and antimicrobial susceptibility testing. Phage typing as a subtyping technique is often complemented with molecular methods like pulsed-field gel electrophoresis (PFGE), which is considered the gold standard for subtyping of Salmonella [2]. Recent studies suggest that multiple-locus variable-number of tandem repeats analysis (MLVA) improves surveillance, detection of outbreaks and of sources of outbreaks of Salmonella and in particular of S

Objectives

Methods

Results

Conclusion