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United States Department of Agriculture

Agricultural Research Service

Title: 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

Authors
item Borucki, Monica
item Kim, S - WSU
item Call, D - WSU
item Smole, S - MA STATE LAB INST
item Pagotto, F - HEALTH CANADA

Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 31, 2004
Publication Date: October 1, 2004
Citation: Borucki, M.K., Kim, S.H., Call, D.R., Smole, S.C., Pagotto, F. 2004. SELECTIVE DISCRIMINATION OF LISTERIA MONOCYTOGENES EPIDEMIC STRAINS USING A MIXED-GENOME DNA MICROARRAY AS COMPARED TO PULSED-FIELD GEL ELECTROPHORESIS, RIBOTYPING AND MULTI-LOCUS SEQUENCE TYPING. Journal of Clinical Microbiology. 42(11):5270-5276.

Interpretive Summary: Listeria monocytogenes is a food-borne bacterial pathogen that can cause serious illness in humans and subsequent epidemiologic investigation requires molecular characterization to allow the identification of specific isolates. L. monocytogenes is usually characterized by serotyping and subtyped using pulsed-field gel electrophoresis (PFGE) or ribotyping. DNA microarrays provide an alternative means to resolve subtype isolates and unlike PFGE and ribotyping, microarrays can be used to identify specific genes that differ among strains. Twenty strains of L. monocytogenes were used to generate a 629 probe microarray that included only potentially informative (polymorphic) gene probe sequences. Fifty-two strains of L. monocytogenes were subtyped using the condensed array, including strains associated with five major listeriosis epidemics. Microarray data grouped strains according to phylogenetic lineage and serotype. Most epidemiologically-linked strains were grouped together and subtyping resolution was the same as PFGE and better than multilocus sequence typing and ribotyping. Additionally, a majority of epidemic strains were grouped together. Statistical analysis of the microarray data 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 advantage in the environment and/or host.

Technical Abstract: Listeria monocytogenes can cause serious illness in humans and subsequent epidemiologic investigation requires molecular characterization to allow the identification of specific isolates. L. monocytogenes is usually characterized by serotyping and subtyped 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 a subsequent 629 probe microarray was constructed using features that included only potentially polymorphic gene probe sequences. Fifty-two strains of L. monocytogenes were genotyped 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 PFGE (AscI and ApaI) and better than multilocus sequence typing (using seven house-keeping 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 that 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 advantage in the environment and/or host.

Last Modified: 9/20/2014
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