الفهرس 
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Abstract
Listeria monocytogenes is a foodborne pathogen, and one of most important zoonotic bacterium with fatality rates up to 20- 30%. It has a great hazard on public health and dairy industry. Milk and dairy products are implicated in most outbreaks of listeriosis all over the world.
This work aimed to investigate the prevalence of Listeria species in milk, feces of dairy cows and pregnant women in two Governorates (Sharkia and Dakahlia) in Egypt. Moreover, this study was carried out to molecularly identify L. monocytogenes to the species level based on 16S rRNA gene and to determine the prevalence of two virulence genes (inlA and inlB) in molecularly identified L. monocytogenes isolates. Finally, the genetic diversity of L. monocytogenes isolated from different sources was determined by ERIC-PCR.
In this study, bacteriological analysis of 350 different samples including; normal raw milk (n=200), mastitis milk (n=50), feces of dairy cows (n=50) and stool of pregnant women (n=50) was carried out for isolation of Listeria spp. on Oxford agar and then the recovered isolates were subjected to biochemical and molecular identification procedures.
The results showed that:
- Out of 350 examined samples, 56 (16%) were contaminated with Listeria spp. using culture techniques, and biochemical tests. Among the 56 isolated Listeria spp. 38 (19%), 6 (12%), 8 (16%) and 4(8%) were recovered from normal raw milk, mastitis milk, feces of dairy cows and stool of pregnant women, respectively. The Listeria spp. isolates from different sources involved L. monocytogenes (4.29%), L. ivanovii (5.14%), L. grayi (2.57%), L. welshimeri (2.57%) and L. innocua (1.43%).
- L. ivanovii was isolated from normal raw milk and mastitis milk (6%, each).
-The prevalence rates of L. monocytogenes represented as 8% from feces of dairy cows followed by 4% from both normal raw milk and stool of pregnant women samples then 2% in mastitis milk samples.
- The prevalence rates of L. welshimeri were 4% in normal raw. However, it was not isolated from mastitis milk and feces of dairy cow.