title: Listeria monocytogenes occurrence and characterization in meat-producing plants.
abstract: OBJECTIVE
  The prevalence, level of contamination and epidemiological profile of Listeria monocytogenes were investigated in two meat-producing plants during a 20-month period.
  
  
  RESULTS
  Sampling for L. monocytogenes was carried out in a cattle slaughterhouse (n = 72) and a swine meat-processing plant (n = 68) during a 20-month period. Swabs and food samples were analysed with the most probable number (MPN) technique for L. monocytogenes and the isolated strains were characterized by AscI-restriction analysis pulsed-field gel electrophoresis (REA-PFGE). Contamination of meat and meat products was always at low level (below 50 MPN per gram). The seven L. monocytogenes positive samples isolated in the bovine slaughterhouse yielded strains with the same REA-PFGE profile. However, the seven strains isolated in the swine meat processing plant showed six different profiles. Two of them showed indistinguishable profiles with L. monocytogenes strains collected from other meat processing facilities located in the same area.
  
  
  CONCLUSIONS
  The genotyping method is a valuable tool to investigate contamination sources. The study of REA-PFGE profiles indicated that environmental contamination was probably responsible for the persistence of over 16 months of one strain of L. monocytogenes in the cattle slaughterhouse. Several meat suppliers could be responsible for the contamination in the pig meat processing facility, and this is confirmed by the finding of some identical strain in other meat processing facilities located in the same area.
authors.affiliation: Dipartimento di Sanità Pubblica Veterinaria e Patologia Animale, Facoltà di Medicina Veterinaria, Alma Mater Studiorum, Università di Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Peccio
authors.forename: T
authors.initials: T
authors.lastname: Autio
authors.forename: H
authors.initials: H
authors.lastname: Korkeala
authors.forename: R
authors.initials: R
authors.lastname: Rosmini
authors.forename: M
authors.initials: M
authors.lastname: Trevisani
mesh_terms: D000003:Abattoirs; D000818:Animals; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D016521:Electrophoresis, Gel, Pulsed-Field; D004866:Equipment Contamination; D008089:Listeria monocytogenes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008088:Listeriosis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D008461:Meat Products / Q000382:microbiology*; D008462:Meat-Packing Industry; D015183:Restriction Mapping; D013552:Swine / Q000382:microbiology*; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology
chemical_list: C078382:endodeoxyribonuclease AscI; D015252:Deoxyribonucleases, Type II Site-Specific