Isolation and Molecular Detection of Listeria monocytogenes in Minced Meat,
Frozen Chicken and Cheese in Duhok Province, Kurdistan Region of Iraq
Saman Said Taha Said Ahmed
*
, Bizhar Ahmed Tayeb, Alind Mahmood Ameen, Sowaila Mekaeel Merza and Yousif Hamed Mohammed Sharif
*
Laboratory Department, Veterinary Directorate in Duhok 1, 1000 Jn Galy Way, 42001 Duhok Province, Iraq
*
Corresponding author: Saman Said Taha Said Ahmed, Laboratory Department, Veterinary Directorate in Duhok 1, 1000 Jn Galy Way, 42001 Duhok Province, Iraq, E-
mail: shokri.mustafa@uqconnect.edu.au
Received date: February 20, 2017; Accepted date: March 07, 2017; Published date: March 13, 2017
Copyright: © 2017 Ahmed SSTS, et al. This is an open-access article distributed under the terms of the creative commons attribution license, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Aims: Listeria monocytogenes (L. monocytogenes) is the food-borne pathogen responsible for listeriosis. It is
considered a serious public health risk, and is spread through the consumption of food products. The disease can
be fatal to humans and animals. The objective of the present study was to isolate and identify L. monocytogenes
from frozen chicken, minced meat, and cheese in Duhok province, Iraq.
Methodology and Results: Between March and October 2015, equal numbers (n=50) of samples of minced
meat, frozen chicken, and cheese were collected (total n=150). Biochemical and microbiological tests, including real-
time PCR, were performed to determine the prevalence of L. monocytogenes in the samples. Out of 150 samples,
20 displayed greyish/black colonies with black halos on Oxford and Palcam agar. of these putative Listeria, 12 were
subsequently identified as L. monocytogenes by PCR. L. monocytogenes was detected in 1 (2%), 7 (14%), and 4
(8%) of isolates from cheese, minced meat, and frozen chicken, respectively.
Conclusion: Significance and Impact of study: Detection of pathogenic bacteria in foods, such as those analysed
in this study, is crucial for safeguarding public health. The qPCR technique offers a rapid and reliable method for
isolation of many foodborne pathogens in different kinds of foods.
Keywords: Listeria monocytogenes; Real time PCR; Identifcation;
Detection; Food
Introduction
Listeria spp. are broadly distributed in the environment. Tey can be
isolated from soil and water Jersik, et al. [1]. A wide range of animal
species can become contaminated by L. monocytogenes, including
mammals, domesticated animals, pets, fsh, birds, and crustaceans
Alsheikh et al. [2].
In mammals, L. monocytogenes can cause premature births and
meningoencephalitis Aznar et al. [3]. L. monocytogenes is a concern to
public health because of its capability to survive or even grow under
harsh conditions [4,5]. Te increasing rate of L. monocytogenes
involvement in food-born outbreaks has led to the requirement for a
rapid method for testing food products. Almost all cases of listeriosis
tend to be food-born, and a number of food items can become
contaminated by L. monocytogenes, including raw chicken meat, raw
minced meat, sof cheese, and fsh. Most of these items are widely
consumed in Iraq’s Kurdistan and Duhok provinces.
A number of molecular biological methods have been described for
detection of L. monocytogenes, including DNA probes and PCR
techniques. Direct detection of L. monocytogenes in food products by
PCR has been reported in several cases Bansal et al. [6], Manzano et al.
[7], Agersborg et al. [8], O’Connor et al. [9] and Hudson et al. [10].
To our knowledge, there is no published data regarding L.
monocytogenes prevalence in food samples from Duhok province. In
fact, there are no ofcial data of food-born listeriosis recorded in
Duhok, as L. monocytogenes is rarely tested for in food samples. Te
objective of the present research was to assess the use of PCR for the
detection of L. monocytogenes in food products, and to determine the
prevalence of Listeria spp. in food products in Duhok, by using
molecular and biochemical methods.
Materials and Methods
Samples (n=150) of diferent food products, including chicken
(n=50), minced meat (n=50), and cheese (n=50), obtained from
diferent supermarkets, restaurants and veterinary quarantine centres
in Duhok province, were tested. All samples had been correctly stored,
and were placed in separate sterile plastic bags to prevent spilling and
cross contamination. Te samples were brought to the laboratory on
crushed ice, and were kept at 4°C until testing (within 4 h).
Food samples were analysed for the presence of Listeria spp. using a
selective enrichment and isolation protocol, as recommended by the
United States Department of Agriculture (USDA) [11].
Microbiological investigation
Samples (25 g) were added to 225 mL of ½ strength Fraser broth
(Conda, Spain), to obtain a 1:10 dilution. All samples were
homogenized (30-60 sec) and incubated (30°C, 24 h). From this
primary enrichment, 0.1 mL was then inoculated into 10 mL of Fraser
broth, and incubated (37°C, 48 h) with shaking. A loopful of the
subsequent culture was streaked on the surface of diferent agars
(PALCAM listeria agar (Conda, Spain) with supplement, and
OXFORD agar (Lab UK) with X122 supplement). Agar plates were
then incubated (37°C, 48 h) and observed (at 24 to 48 h incubation)
Ahmed et al., J Food Microbiol Saf Hyg 2017, 2:1
DOI: 10.4172/2476-2059.1000118
Research Article Open Access
J Food Microbiol Saf Hyg, an open access journal
ISSN:2476-2059
Volume 2 • Issue 1 • 1000118
Journal of Food: Microbiology, Safety
& Hygiene
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ISSN: 2476-2059