Risk factors associated with listeria in raw milk

Abstract EN

Listeriosis has emerged as a serious food borne disease, and many recent outbreaks have generated much interest in investigating behavior of listeria in foods and environmental samples.

A total of 100 random samples of raw milk, water, feeds and feces (25 sample each) were collected from several farms in Kafr El-Sheikh and Kotor cities, Egypt, and examined for presence of Listeria spp.

Isolated cultures were biochemically identified and suspected L.

monocytogenes cultures were confirmed by PCR Protocol.

Results reveal that Listeria spp.

were detected in one (4 %), 3 (12 %) and 2 (8 %) of raw farm milk, feed and fecal samples respectively and failed to be detected in water samples.

Among 25 strains of Listeria spp.

isolates, 18 were biochemically identified while 7 were untypable.

Biochemically identified Listeria spp.

were L.

monocytogenes that detected in one (4 %), 2 (8 %) and 2 (8 %) of raw farm milk, feed and fecal samples respectively.

L.

innocua was found in 2 (8 %) and one (4 %) samples of animal feeds and feces respectively, while L.

welshimeri was isolated from one (4 %) and 2 (8 %) of feed and fecal samples respectively.

Suspected L.

monocytogenes isolates were tested for multiple virulence-associated genes of L.monocytogenes by PCR protocol.

Results revealed that only 3 isolates were confirmed by PCR to be L.

monocytogenes reflecting only one (4 %) sample each of raw farm milk, animal feed and fecal samples to be contaminated by L.

monocytogenes.

Risk factors associated with Listeria, public health importance as well as hygienic measures and recommendations are discussed.