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.