Pilot Study To Evaluate Microarray Hybridization as a Tool for Salmonella enterica Serovar Typhimurium StrainDifferentiation

Abstract

In developed countries, Salmonella enterica subspecies 1 serovars Enteritidis and Typhimurium range among the most common causes of bacterial food-borne infections. The surveillance and typing of epidemic Salmonella strains are important tools in epidemiology. Usually, Salmonella enterica subspecies 1 serovars are differentiated by serotyping for diagnostic purposes. Further differentiation is done by phage typing as well as molecular typing techniques. Here we have designed and evaluated a prototype DNA microarray as a tool for serovar Typhimurium strain differentiation. It harbors 83 serovar Typhimurium probes obtained by differential subtractive hybridization and from the public database. The microarray yielded reproducible hybridization patterns in repeated hybridizations with chromosomal DNA of the same strain and could differentiate five serovar Typhimurium reference strains (DT204, DT104, DT208, DT36, and LT2). Furthermore, the microarray identified two distinct groups among 13 serovar Typhimurium DT104 strains. This correlated with observations from pulsed-field gel electrophoresis analysis. Twenty-three further serovar Typhimurium strains were analyzed to explore future directions for optimization of the simple 83-probe DNA microarray. The data presented here demonstrate that DNA microarrays harboring small numbers of selected probes are promising tools for serovar Typhimurium strain typing.Salmonella spp. are pathogenic enterobacteria which can cause food-borne diseases ranging from a mild gastroenteritis to systemic infections (typhoid fever). In developed countries, infections with Salmonella enterica subspecies 1 serovars Enteritidis and Typhimurium range among the most common causes of bacterial food-borne infections.For diagnostic purposes, Salmonella enterica subspecies 1 serovars are differentiated by serotyping (28), which allows reliable identification of organisms that cause infections associated with higher risks (i.e., serovar Typhi). For epidemiological surveys, detection of outbreaks, and uncovering of the chains of transmission, serotyping is insufficient because serovar Enteritidis and serovar Typhimurium often account for Ͼ80% of all human salmonelloses. For further differentiation, serotyping is complemented by phage typing as well as molecular typing techniques.During the past decades serovar Typhimurium strains have been differentiated by phage typing (1). The Anderson phage typing scheme is based on the empirical observation that certain phages can cause lytic infections in one serovar Typhimurium strain but not another. A set of 34 bacteriophages allows more than 200 patterns of resistance or sensitivity, the "phage types" (definitive phage types [DTs]), to be distinguished. Phage typing has proven very useful for distinguishing many serovar Typhimurium strains. It has been invaluable for surveillance of the emergence and spread of epidemic serovar Typhimurium strains (i.e., DT204c and DT104) during the past decades (23,40,(42)(43)(44)49).In spite of its success, phage typing has ...

Characterisation of multidrug-resistant Salmonella Typhimurium 4,[5],12:i:- DT193 strains carrying a novel genomic island adjacent to the thrW tRNA locus

“…This indicates either that diversification occurred after emergence of 4,[5],12:i:-strains or that this serotype arose due to multiple independent events in the different countries . Pelludat et al (2005) used a microarray-based subtractive hybridisation method to subclassify S. Typhimurium strains. They could clearly correlate hybridisation pattern and phage type of DT104 and DT204 strains, while DT193 isolates appeared to be heterogeneous (supplementary data in Pelludat et al, 2005).…”

Probe Hybridization Array Typing: a Binary Typing Method for Escherichia coli

“…In binary typing, each strain is assigned a signature based on the presence or absence of a set of defined DNA sequences rather than allelic profiles. Binary typing using comparative genomic hybridization, containing all of the open reading frames (ORFs) of a sequenced genome (genomotyping), has been demonstrated for typing clinical bacterial Campylobacter and Salmonella strains (13,18). In this method, strains can be typed for the presence or absence of all the coding regions on the bacterial genome.…”

Poultry-Associated Salmonella enterica subsp. enterica Serovar 4,12:d:− Reveals High Clonality and a Distinct Pathogenicity Gene Repertoire

“…However, whole-genome arrays reflect only one genome of one strain. Because of many serovar or strain genome variations described for Salmonella, thematic arrays were developed, such as arrays specially targeting genes involved in resistance profiles (2,17,32), phage types (23), or serovars (33,35). A condensed selection of 109 various Salmonella genetic markers comprising the detection of flagellar and somatic antigen-encoding genes, important virulence genes, phage-associated genes, and antibiotic resistance determinants have been used to show the usefulness of DNA microarrays for the discriminative characterization of Salmonella serovars (18).…”