Multi Locus Variable-Number Tandem Repeat (MLVA) Typing Tools Improved the Surveillance of Salmonella Enteritidis: A 6 Years Retrospective Study

Abstract

Surveillance of Salmonella enterica subsp. enterica serovar Enteritidis is generally considered to benefit from molecular techniques like multiple-locus variable-number of tandem repeats analysis (MLVA), which allow early detection and confinement of outbreaks. Here, a surveillance study, including phage typing, antimicrobial susceptibility testing and MLVA on 1,535 S. Enteritidis isolates collected between 2007 and 2012, was used to evaluate the added value of MLVA for public health surveillance in Belgium. Phage types PT4, PT8, PT21, PT1, PT6, PT14b, PT28 and PT13 dominate the Belgian S. Enteritidis population. The isolates of S. Enteritidis were most frequently susceptible to all antibiotics tested. 172 different MLVA profiles were detected, of which 9 frequent profiles included 67.2% of the S. Enteritidis population. During a serial passage experiment on selected isolates to investigate the in vitro stability of the 5 MLVA loci, no variations over time were observed indicating that the MLVA profiles were stable. The MLVA profile of isolates originating from different outbreaks in the Democratic Republic of the Congo (DRC) between 2010 and 2011 were distinct from any of the MLVA profiles found in Belgian isolates throughout the six year observational period and demonstrates that MLVA improves public health surveillance of S. Enteritidis. However, MLVA should be complemented with other subtyping methods when investigating outbreaks is caused by the most common MLVA profile.

Non-typhoidal Salmonella intestinal carriage in a Schistosoma mansoni endemic community in a rural area of the Democratic Republic of Congo

“…Salmonella Typhimurium (n = 4) and Salmonella Enteritidis isolates (n = 5) were sent to the Institute of Public health (IPH, Brussels, Belgium) for multi-locus variable-numbers tandem repeat analysis (MLVA) as previously described [42][43][44]. MLVA profiles were attributed based on the number of tandem repeats on five loci (SENTR7, SENTR5, SENTR6, SENTR4, SE3 for Salmonella Enteritidis and STTR9, STTR5, STTR6, STTR10, STTR3 for Salmonella Typhimurium isolates).…”

Molecular Subtyping of <i>Salmonella enterica</i> Serovar Typhi by Pulsed-Field Gel Electrophoresis and Multiple-Locus Variable-Number Tandem-Repeat Analysis in India: Their Association with Antimicrobial Resistance Profiles

“…The VNTR loci investigated in this study also do not reside in resistance genes. AST is a typing method used in public health surveillance, but MLVA typing is useful in epidemiological surveillance of S. Enteritidis due to low prevalence of antimicrobial resistance in those isolates (19). In this study, 5 resistance profiles also did not represent the complete diversity among them as represented by 59 MLVA types (Fig.…”

“…MLVA has been particularly effective in typing homogenous clones, including Yersinia pestis (15), Escherichia coli O157:H7 (16), Clostridium difficile (17), and Mycobacterium tuberculosis (18). In Salmonella enterica (S. enterica), a few serovars such as Enteritidis (19), Typhimurium (20), and Typhi (10) have been studied by MLVA. Moreover, MLVA is cost-effective, accessible to any laboratory equipped with minimum molecular biology equipment, and suitable for large-scale standardization.…”

Foodborne bacteria in dairy products: Detection by molecular techniques

“…However, PFGE is time-consuming and laborious to perform (Liu et al, 2016), which makes it less suitable for typing many isolates, and it requires rigorous standardization of the protocols (Bertrand et al 2015). PFGE also lacks the discriminatory capacity and phylogenetic basis of more advanced methods .…”

“…MLVA is a molecular subtyping method based on amplification and fragment size analysis of the number of repeats in the variable-number tandem repeats region of the bacterial genome (Bertrand et al 2015). It is rapid and highly reproducible, and the results are easily interpreted and standardized among laboratories.…”