الكشف عن الليستيريا مونوسايتوجين في الحليب الخام ومشتقاته في محافظة كربلاء

Detection of listeria monocytogenes in Raw milk and Dairy products in Kerbala Province

Abstract
The objective of the present study was to detection of Listeria monocytogenes. in raw cows’ milk and dairy products.
Two hundred fifty Samples of raw milk and dairy products which include (yogurt, cheese, Butter) were collected randomly in interval from 1st January to 30 June 2022.
In Kerbala province the samples of milk were collected from cows in local farms while the samples of dairy products were collected from markets and sell points, All samples were treated according to standard protocols of Listeria monocytogenes and delivered to laboratory for analyzing.
The study of physical features for the samples of milk and dairy products which contaminated with Listeria Monocytogenes were revealed change in color, smell and taste, while the biochemical reactions have been showed decrease in pH, and increase in chloride while, catalase and white side test given positive reaction.
The bacteriological study which included isolation and identification of listeria monocytogenes from animal sources by using selective media for listeria monocytogenes, which is the (oxford agar) from (Hi media) Company for culturing. The isolates of Listeria Monocytogenes was showed on selective media as black colonies also all isolates of Listeria Monocytogenes were given positive results for catalase test.
Molecular study of Listeria Monocytogenes was done by conventional PCR technique after DNA extraction by using a DNA extraction Kit.
Four specific duplex primers (Hly-1-f, Hly-2-R, List-F, List-R) were designed on the basis of a divergent region of the L. monocytogenes genome that was by means of microarray analysis directed to the Hly gene, isolates of L. Monocytogenes were identified and study of genetic variation between local listeria monocytogenes isolates which was carried out using the DNA sequencing process which confirming contamination of raw milk and dairy products samples.

The sensitivity test of all bacteria of isolates to antibiotics was studied, as it was observed that they were sensitive to some antibiotics include [Neomycin with sensitivity zone (28 mm), Ciprofloxacin (10 mm), Gentamycin (15 mm), Chloramphenicol (20 mm)] However, resistance to the antibiotics [Amoxilin with Resistance zone (10 mm), Ceftriaxone (5mm)].
The incidence of listeria monocytogenes varied by area from 32% in al-Gadwal Algarbi to 20 % in each of Al-Husainia, Al-Hindia and Ain Altamer with total incidence of 10 %.
The study was concluded contamination of raw milk with Listeria monocytogenes in Karbala city and its outskirts, milk and dairy products are one of the main sources for L. Monocytogenes spreads to human. the highest percentage of listeria Monocytogenes occurrence was in winter season more than in the summer, especially January and February.