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Selective discrimination of Listeria monocytogenes epidemic strains by a mixed-genome DNA microarray compared to discrimination by pulsed-field gel electrophoresis, ribotyping, and multilocus sequence typing.

ABSTRACT: Listeria monocytogenes can cause serious illness in humans, and subsequent epidemiological investigation requires molecular characterization to allow the identification of specific isolates. L. monocytogenes is usually characterized by serotyping and is subtyped by using pulsed-field gel electrophoresis (PFGE) or ribotyping. DNA microarrays provide an alternative means to resolve genetic differences among isolates, and unlike PFGE and ribotyping, microarrays can be used to identify specific genes associated with strains of interest. Twenty strains of L. monocytogenes representing six serovars were used to generate a shotgun library, and subsequently a 629-probe microarray was constructed by using features that included only potentially polymorphic gene probe sequences. Fifty-two strains of L. monocytogenes were genotyped by using the condensed array, including strains associated with five major listeriosis epidemics. Cluster analysis of the microarray data grouped strains according to phylogenetic lineage and serotype. Most epidemiologically linked strains were grouped together, and subtyping resolution was the same as that with PFGE (using AscI and ApaI) and better than that with multilocus sequence typing (using six housekeeping genes) and ribotyping. Additionally, a majority of epidemic strains were grouped together within phylogenetic Division I. This epidemic cluster was clearly distinct from the two other Division I clusters, which encompassed primarily sporadic and environmental strains. Discriminant function analysis allowed identification of 22 probes from the mixed-genome array that distinguish serotypes and subtypes, including several potential markers that were distinct for the epidemic cluster. Many of the subtype-specific genes encode proteins that likely confer survival advantages in the environment and/or host.

SUBMITTER: Borucki MK

PROVIDER: S-EPMC525159 | biostudies-literature | 2004 Nov

REPOSITORIES: biostudies-literature

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Selective discrimination of Listeria monocytogenes epidemic strains by a mixed-genome DNA microarray compared to discrimination by pulsed-field gel electrophoresis, ribotyping, and multilocus sequence typing.

Borucki Monica K MK Kim So Hyun SH Call Douglas R DR Smole Sandra C SC Pagotto Franco F

Journal of clinical microbiology 20041101 11

Listeria monocytogenes can cause serious illness in humans, and subsequent epidemiological investigation requires molecular characterization to allow the identification of specific isolates. L. monocytogenes is usually characterized by serotyping and is subtyped by using pulsed-field gel electrophoresis (PFGE) or ribotyping. DNA microarrays provide an alternative means to resolve genetic differences among isolates, and unlike PFGE and ribotyping, microarrays can be used to identify specific gene ...[more]

PMID: 15528725

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Project description:UnlabelledListeria monocytogenes is a ubiquitous bacterium that may cause the foodborne illness listeriosis. Only a small amount of data about the population genetic structure of strains isolated from food is available. This study aimed to provide an accurate view of the L. monocytogenes food strain population in France. From 1999 to 2014, 1,894 L. monocytogenes strains were isolated from food at the French National Reference Laboratory for L. monocytogenes and classified according to the five risk food matrices defined by the European Food Safety Authority (EFSA). A total of 396 strains were selected on the basis of different pulsed-field gel electrophoresis (PFGE) clusters, serotypes, and strain origins and typed by multilocus sequence typing (MLST), and the MLST results were supplemented with MLST data available from Institut Pasteur, representing human and additional food strains from France. The distribution of sequence types (STs) was compared between food and clinical strains on a panel of 675 strains. High congruence between PFGE and MLST was found. Out of 73 PFGE clusters, the two most prevalent corresponded to ST9 and ST121. Using original statistical analysis, we demonstrated that (i) there was not a clear association between ST9 and ST121 and the food matrices, (ii) serotype IIc, ST8, and ST4 were associated with meat products, and (iii) ST13 was associated with dairy products. Of the two major STs, ST121 was the ST that included the fewest clinical strains, which might indicate lower virulence. This observation may be directly relevant for refining risk analysis models for the better management of food safety.ImportanceThis study showed a very useful backward compatibility between PFGE and MLST for surveillance. The results enabled better understanding of the population structure of L. monocytogenes strains isolated from food and management of the health risks associated with L. monocytogenes food strains. Moreover, this work provided an accurate view of L. monocytogenes strain populations associated with specific food matrices. We clearly showed that some STs were associated with food matrices, such as meat, meat products, and dairy products. We opened the way to source attribution modeling in order to quantify the relative importance of the main food matrices.

Project description:BACKGROUND: Listeriosis is a severe infection which mainly affects pregnant women, neonates and immuno-compromised adults. ANSES's Laboratory for Food safety has been the European Union Reference Laboratory (EURL) for L. monocytogenes in the food chain since 2006. Pulsed Field Gel Electrophoresis (PFGE) is routinely used in the EURL for the surveillance of L. monocytogenes isolated from foods, animals and the environment. One of the main EURL activities is to evaluate alternative molecular subtyping methods to PFGE, and integrate their use within the National Reference Laboratories (NRL) network. Since 2008, the United Kingdom (UK)-NRL for L. monocytogenes at the Health Protection Agency (HPA), London, has used fluorescent Amplified Fragment Length Polymorphism (fAFLP) for the routine surveillance of L. monocytogenes isolated from human clinical cases, food and food processing environments in the UK. This study compares fAFLP with PFGE for subtyping L. monocytogenes. RESULTS: A panel of 109 L. monocytogenes isolates from either human cases of listeriosis, foods, food processing environments and animals were used for the comparative evaluation. Among these, 2 strains were tested from duplicate culture by both methods. The panel also included field isolates, isolates associated with outbreaks or sporadic cases and reference strains. The two strains tested in duplicate displayed the same fAFLP and PFGE types. Strains known to be epidemiologically associated with one another were found to have unique PFGE and fAFLP types. FAFLP and PFGE divided the strains into 76 and 82 distinct profiles, or types, respectively. The discriminatory index calculated was 0.993 and 0.996 for fAFLP and PFGE, respectively. CONCLUSIONS: The discriminatory ability of fAFLP was similar to that of PFGE for the subtyping of L. monocytogenes isolates. As a less labour intensive technique fAFLP may be a better method to use than PFGE in investigating outbreaks of human listeriosis and tracking the source of contamination in food processing facilities in real time.

Dataset Information

Selective discrimination of Listeria monocytogenes epidemic strains by a mixed-genome DNA microarray compared to discrimination by pulsed-field gel electrophoresis, ribotyping, and multilocus sequence typing.

Publications

Selective discrimination of Listeria monocytogenes epidemic strains by a mixed-genome DNA microarray compared to discrimination by pulsed-field gel electrophoresis, ribotyping, and multilocus sequence typing.

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