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Invading slugs (Arion vulgaris) can be vectors for Listeria monocytogenes

Gismervik, K., Aspholm, M., Rørvik, L.M., Bruheim, T., Andersen, A., Skaar, I.
Journal of applied microbiology 2015 v.118 no.4 pp. 809-816
Arion, Listeria monocytogenes, excretion, feces, gardens, grass silage, listeriosis, meadows, mucus, multilocus sequence typing, ruminants, slugs, tissues, vegetable crops
AIMS: Listeriosis is a frequent silage‐associated disease in ruminants. The slugs Arion vulgaris are invaders in gardens, vegetable crops and meadows for silage production. Field and laboratory studies were conducted to clarify whether slugs could host Listeria monocytogenes and thereby constitute a threat to animal feed safety. METHODS AND RESULTS: Selective culture of L. monocytogenes from 79 pooled slug samples (710 slugs) resulted in 43% positive, 16% with mean L. monocytogenes values of 405 CFU g⁻¹slug tissues. Of 62 individual slugs cultured, 11% also tested positive from surface/mucus. Multilocus sequence typing analysis of 36 isolates from different slug pools identified 20 sequence types belonging to L. monocytogenes lineages I and II. Slugs fed ≅4·0 × 10⁵ CFUL. monocytogenes, excreted viable L. monocytogenes in faeces for up to 22 days. Excretion of L. monocytogenes decreased with time, although there were indications of a short enrichment period during the first 24 h. CONCLUSIONS: Arion vulgaris may act as a vector for L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Highly slug‐contaminated grass silage may pose a potential threat to animal feed safety.