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Faecal prevalence and strain diversity of Listeria monocytogenes in healthy cattle, sheep and swine herds in northern Spain

Abstract number: P641

Esteban J., Oporto B., Aduriz G., Juste R., Hurtado A.

Objectives: Although the incidence of human listeriosis is low compared to salmonellosis or campylobacteriosis (0.88 cases per 100,000 inhabitants per annum in the last 5 years in the Basque Country), Listeria monocytogenes is among the most important foodborne bacterial pathogens due to the high mortality rate (20–30%) and severity of the disease. L. monocytogenes is a ubiquitous organism that inhabits the intestinal tract of various livestock species that act as major reservoirs and source of human infection via faecal contamination of food products. The aim of this study was to determine the prevalence and strain diversity of L. monocytogenes in healthy ruminants and swine farms.

Methods: Faecal samples from 30 animals per farm were collected from 343 farms (120 ovine, 124 beef cattle, 82 dairy cattle and 17 porcine) and screened in pools by an automated enzyme-linked fluorescent immunoassay (VIDAS® LMO2, bioMérieux). Positive samples were subcultured onto the selective and differential agar ALOA and biochemically confirmed. Within-herd prevalence of L. monocytogenes was investigated by individually analysing 50 animals from a selection of pool-positive herds. Isolates were characterised by serotyping and ApaI PFGE analysis.

Results:L. monocytogenes was isolated from 46.3% of dairy cattle, 30.6% beef cattle and 14.2% ovine farms, but not from swine. Within-herd prevalences established by individual testing of 197 sheep (4 herds) and 221 cattle (5 herds was 1.5% (0.0–4.1%) and 21.3% (5.1–72.3%), respectively. Serotyping of 114 isolates (20 ovine and 94 bovine) identified complex 4b the most prevalent (81.7%), followed by 1/2a (14.0%), 1/2b (2.1%) and 4c and 4e (1.1% each). Distribution of serotypes varied slightly among the different host species. PFGE analysis performed on 67 isolates indicated that the L. monocytogenes population in Basque farms is genetically highly diverse and identified the presence of different strains within each farm.

Conclusion: Prevalence values observed in ruminants indicate that good management practices and control strategies at the production level are crucial to reduce L. monocytogenes contamination in the live animal at the primary production level before entry to the slaughterhouse to reduce risk of human infection.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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