title: Similar Listeria monocytogenes pulsotypes detected in several foods originating from different sources.
abstract: The purpose of the study was to obtain fingerprinting data of Listeria monocytogenes strains isolated in various foods to determine possible associations of strains with product type, producer, country or isolation time. Two hundred and ninety-five L. monocytogenes strains originating from food items of 41 producers of 10 countries were characterized by pulsed-field gel electrophoresis (PFGE) typing. Combination of AscI and ApaI macrorestriction patterns (MRP) yielded 66 different pulsotypes. Ten pulsotypes were common to two or more product types and 17 pulsotypes were detected in foods of more than one producer having no apparent association with each other. Similar pulsotypes of L. monocytogenes were recovered in products of different countries over several years. Some of the pulsotypes were recurrently recovered from the same product of the same producer, suggesting a possible persistence of these strains in the processing plant. However, some of the recurrently isolated L. monocytogenes pulsotypes were repeatedly found in products of several producers, which may indicate that persistent houseflora strains are not always producer-specific. Furthermore, the similarity of macrorestriction patterns expressed as clusters, based on the numerical analysis of macrorestriction patterns, was not found to correlate with product type, country, producer or year of isolation. Our data suggest a wide geographical and temporal distribution of a number of L. monocytogenes strains isolated in food products. The existence of similar L. monocytogenes strains in various food products of several producers should be considered if food strain fingerprint results are used to help trace the vehicles for infections.
authors.affiliation: Department of Food and Environmental Hygiene, Faculty of Veterinary Medicine, University of Helsinki, Finland. tiina.jo.autio@helsinki.fi
authors.forename: Tiina
authors.initials: T
authors.lastname: Autio
authors.forename: Janne
authors.initials: J
authors.lastname: Lundén
authors.forename: Maria
authors.initials: M
authors.lastname: Fredriksson-Ahomaa
authors.forename: Johanna
authors.initials: J
authors.lastname: Björkroth
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Sjöberg
authors.forename: Hannu
authors.initials: H
authors.lastname: Korkeala
mesh_terms: D015373:Bacterial Typing Techniques; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis*; D015252:Deoxyribonucleases, Type II Site-Specific; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005516:Food Microbiology; D005525:Food-Processing Industry; D016680:Genome, Bacterial; D008089:Listeria monocytogenes / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D010802:Phylogeny; D015183:Restriction Mapping
chemical_list: D004269:DNA, Bacterial; C078382:endodeoxyribonuclease AscI; D015252:Deoxyribonucleases, Type II Site-Specific; C038485:GGGCCC-specific type II deoxyribonucleases