Presence and growth of Listeria monocytogenes in naturally-contaminated meats.

A total of 101 retail samples of pâté were analysed for the presence of Listeria spp., with 12 and seven samples respectively, found to contain L. innocua and L. monocytogenes, and one each containing L. welshimeri and L. ivanovii. The ability of Listeria spp. to grow on these pâté products was assessed over a 3-week storage period at 4 degrees C. L. monocytogenes was able to survive on the four naturally-contaminated pâtés tested, but growth was only apparent for L. innocua in a turkey-based pâté. Similar findings were noted with growth studies done with L. monocytogenes on naturally-contaminated wieners, ham and turkey breast. Very low numbers (< 10 cfu/g) of the organism were found initially on these products, with L. monocytogenes being found capable of surviving for long periods at 4 degrees C, but being incapable of multiplying. Similarly, pâtés artificially-inoculated with L. monocytogenes showed survival but not growth of the organism over a 3-week storage period at 4 degrees C.