Results
Colonies of L. monocytogenes were small 1-2 mm in diameter and transparent with smooth borders. Narrow zones of Beta haemolysis, which were almost under the colonies, were seen. Microscopically, these were Grampositive and oval rods. When cultured on semisolid media, the organism gave umbrella shaped growth. By “hanging-drop method” a typical “tumbling motility” was observed. The organism hydrolyzed aesculin. L. monocytogenes fermented L-rhamnose but mannitol and D-xylose were not fermented. As a result of “Anton test” on inoculation of the organism into conjunctiva of rabbits, the organism produced keratoconjunctivitis within 36 hrs. Based on growth on medium under cold enrichment, fresh poultry meat and meat products showed 10-12.5% prevalence of listeria species whereas frozen poultry meat products showed 17.5-25%. In case of inanimates (chopping board, mincing machine and cleaning cloths) prevalence ranged from 30 to 37.5% as shown in Table 1 On the basis of Anton test, aesculin test and sugar fermentation tests L.
monocytogenes was found in 2.5-5% of fresh poultry meat samples, in 7.5 to 12.5% of frozen poultry meat samples and in 10-17.5% of other inanimate samples as shown in Table 2. Serotyping identified that 7.18% out of 9.68% L.monocytogenes belonged to serotype 1 and 2.5% belonged to serotype 4 as shown in Table 3.