title: Characteristics and frequency of detection of fecal Listeria monocytogenes shed by livestock, wildlife, and humans.
abstract: Listeria monocytogenes is a facultative intracellular pathogen that can be carried asymptomatically in various animals and can be shed in feces. We investigated the prevalence and characteristics of L. monocytogenes isolated from livestock, wildlife, and human potential sources of contamination in 2 areas in Ontario, Canada. From February 2003 to November 2005, a total of 268 fecal samples were collected from different animals. Listeria monocytogenes was isolated using selective enrichment, isolation, and confirmation procedures, and 15 samples (6%) yielded to the isolation of 84 confirmed strains. Listeria monocytogenes was isolated from livestock (beef and dairy), wildlife (deer, moose, otter, and raccoon), and human (biosolids and septic) fecal sources. Thirty-two isolates were from serovar 1/2a, 34 from serovar 1/2b, 1 from serovar 3a, and 17 from serovar 4b. Listeria monocytogenes populations were resolved into 13 EcoRI ribotypes, and 18 ApaI and 18 AscI pulsotypes, with Simpson indexes of discrimination of 0.878 and 0.907, respectively. A majority (59%) of L. monocytogenes isolates exhibited potential virulence linked to the production of a functional internalin A, which was supported by higher entry into Caco-2 cells (9.3%) than isolates producing truncated and secreted internalin A (1.3% of entry). Listeria monocytogenes fecal isolates were on average resistant to 6.4 +/- 2.5 antibiotics out of 17 tested, and potentially virulent isolates exhibited an enhanced resistance to kanamycin, gentamicin, streptomycin, and rifampicin. Livestock, wildlife, and human L. monocytogenes fecal communities exhibited overlapping but distinct populations, and some genotypes and phenotypes were similar to those previously described for surface water isolates in the same area.
authors.affiliation: Southern Crop Protection and Food Research Center, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.
authors.forename: Emilie
authors.initials: E
authors.lastname: Lyautey
authors.forename: Alain
authors.initials: A
authors.lastname: Hartmann
authors.forename: Franco
authors.initials: F
authors.lastname: Pagotto
authors.forename: Kevin
authors.initials: K
authors.lastname: Tyler
authors.forename: David R
authors.initials: DR
authors.lastname: Lapen
authors.forename: Graham
authors.initials: G
authors.lastname: Wilkes
authors.forename: Pascal
authors.initials: P
authors.lastname: Piveteau
authors.forename: Aurélie
authors.initials: A
authors.lastname: Rieu
authors.forename: William J
authors.initials: WJ
authors.lastname: Robertson
authors.forename: Diane T
authors.initials: DT
authors.lastname: Medeiros
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Edge
authors.forename: Victor
authors.initials: V
authors.lastname: Gannon
authors.forename: Edward
authors.initials: E
authors.lastname: Topp
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology*; D000835:Animals, Wild / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018938:Caco-2 Cells; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D016521:Electrophoresis, Gel, Pulsed-Field; D005243:Feces / Q000382:microbiology*; D006801:Humans; D008089:Listeria monocytogenes / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification* / Q000472:pathogenicity; D008088:Listeriosis / Q000453:epidemiology* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D021521:Ribotyping; D012703:Serotyping; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D015246:Deoxyribonuclease EcoRI