Listeria monocytogenes is a Gram positive, aerobic, facultative anaerobic and nonacid fast bacterium, which can cause the disease listeriosis in both human and animals. It is widely distributed thoroughout the environment and has been isolated from various plant and animal food products associated with listeriosis outbreaks.

Contaminated ready-to-eat food products such as gravad and cold-smoked salmon and rainbow trout have been associated with human listeriosis in Sweden. The aim of this study was to analyse the occurrence and level of L. monocytogenes in
gravad and cold-smoked salmon (Salmo salar) products packed under vacuum or modified atmosphere from retail outlets in Sweden. Isolated strains were characterized by serotyping and the diversity of the strains within and between
producers were determined with PFGE (Pulsed-field gel electrophoresis). The characterized fish isolates were compared with previously characterized human strains.
L. monocytogenes was isolated from 11 (three manufacturers) of 56 products analysed. This included gravad salmon products from three manufacturers and cold-smoked salmon from one manufacturer. The highest level of L. monocytogenes found was 1500 cfu/g from a cold-smoked salmon product but the level was low (<100 cfu/g) in most of the products. Serovar 1/2a was predominant,
followed by 4b. Three products of gravad salmon harboured more than one serovar. PFGE typing of the 56 salmon isolates detected five Asc I types: four types were identical to human clinical strains with Asc I and one was identical and one was closely related to human clinical strains with Apa I. Isolation of identical or closely related L. monocytogenes strains from human clinical cases of listeriosis and gravad and cold-smoked salmon suggested that these kinds of products are possible sources of listeriosis in Sweden. Therefore, these products should be considered risk products for human listeriosis.

Listeria monocytogenes, a food-borne pathogen

Control of Salmonella in foods by using essential oils: A review

The initial development of intestinal microbiota in poultry plays an important role in production performance, overall health and resistance against microbial infections. Multiplexed sequencing of 16S ribosomal RNA gene amplicons is often used in studies, such as feed intervention or antimicrobial drug trials, to determine corresponding effects on the composition of intestinal microbiota. However, considerable variation of intestinal microbiota composition has been observed both within and across studies. Such variation may in part be attributed to technical factors, such as sampling procedures, sample storage, DNA extraction, the choice of PCR primers and corresponding region to be sequenced, and the sequencing platforms used. Furthermore, part of this variation in microbiota composition may also be explained by different host characteristics and environmental factors. To facilitate the improvement of design, reproducibility and interpretation of poultry microbiota studies, we have reviewed the literature on confounding factors influencing the observed intestinal microbiota in chickens. First, it has been identified that host-related factors, such as age, sex, and breed, have a large effect on intestinal microbiota. The diversity of chicken intestinal microbiota tends to increase most during the first weeks of life, and corresponding colonization patterns seem to differ between layer- and meat-type chickens. Second, it has been found that environmental factors, such as biosecurity level, housing, litter, feed access and climate also have an effect on the composition of the intestinal microbiota. As microbiota studies have to deal with many of these unknown or hidden host and environmental variables, the choice of study designs can have a great impact on study outcomes and interpretation of the data. Providing details on a broad range of host and environmental factors in articles and sequence data repositories is highly recommended. This creates opportunities to combine data from different studies for meta-analysis, which will facilitate scientific breakthroughs toward nutritional and husbandry associated strategies to improve animal health and performance.

/pdf/host-and-environmental-factors-affecting-the-intestinal-aeryex8qgp.pdf

Host and Environmental Factors Affecting the Intestinal Microbiota in Chickens

Background Microwave processing techniques have been extensively used in the food industry due to its significant reduction in cooking time and energy consumption. Microwave processing technologies such as microwave drying, heating and sterilizing play a significant role in food quality and safety control. However, few reviews have been published in recent years summarizing the latest developments in the application of microwave technology in the food industry. Scope and approach This review focuses on recent applications of microwave processing technologies including microwave drying, heating, and sterilizing in fruit (banana, apple, olive, sour cherries, pomegranate arils, blueberries, kiwifruit, aronia, strawberry, and grape tomato), vegetables (potato, bamboo shoot, purslane leaves, onion, green bean, pumpkin, eggplant, edamame, sea tangle, garlic, kale, red cabbage, tomato, cassava, lentils, chickpea, broccoli, Brussels sprouts, cauliflower, jalapeno peppers, and coriander foliage), and meat products (sardine fish, restructured silver carp slices, sea cucumber, beef semitendinosus muscle, bovine supraspinatus muscle, camel longissimus dorsi muscle, foal meat, bovine gluteus medium muscle, chicken steak, mature cows semimembranosus and semitendinosus muscles, kavurma (a ready-to-eat meat product), salmon, cod, drumettes, and beef slices), changes in product quality as affected with microwave processing are discussed in details, and future directions of research are presented. Key findings and conclusions Microwave drying has the advantages of low energy consumption and high efficiency as compared to conventional drying, while producing more porous structure of foods. Microwave drying usually combines with other conventional drying to enhance the quality of a food product. Compared with the traditional method, microwave heating or cooking can generally retain higher levels of bioactive components, antioxidant activity and attractive color of vegetables, while microwave cooking with water can cause a serious drop in nutrients due to leaching and thermal liability. Microwave sterilization has the capacity to completely inactivate microorganisms and effectively destroy enzyme activity, and less effect on antioxidant activity, texture and color of food products compared with conventional pasteurization.

Microwave processing techniques and their recent applications in the food industry

The ability to detect low numbers of microbial cells in food and clinical samples is highly valuable but remains a challenge. Here we present a detection system (called 'APC-Cas') that can detect very low numbers of a bacterial pathogen without isolation, using a three-stage amplification to generate powerful fluorescence signals. APC-Cas involves a combination of nucleic acid-based allosteric probes and CRISPR-Cas13a components. It can selectively and sensitively quantify Salmonella Enteritidis cells (from 1 to 105 CFU) in various types of samples such as milk, showing similar or higher sensitivity and accuracy compared with conventional real-time PCR. Furthermore, APC-Cas can identify low numbers of S. Enteritidis cells in mouse serum, distinguishing mice with early- and late-stage infection from uninfected mice. Our method may have potential clinical applications for early diagnosis of pathogens.

/pdf/sensitive-detection-of-a-bacterial-pathogen-using-allosteric-46juwmarps.pdf

Sensitive detection of a bacterial pathogen using allosteric probe-initiated catalysis and CRISPR-Cas13a amplification reaction.

Poultry meat has been identified as one of the principal foodborne sources of Salmonella. In this preliminary study the prevalence of Salmonella spp. and its typhimurium serovar contamination of broiler carcasses, were determined. Using the rinse test method, numbers of 60 samples, representing 20 broiler flocks, were collected from poultry carcasses after the chilling stage in the processing line at a commercial broiler slaughtering facility in Mashhad, Iran. The presence of Salmonella spp and Salmonella typhimurium in collected samples were assessed by performing the pre-enrichment and enrichment culture, followed by multiplex- PCR assay. The primers were selected from the invA and fliC genes, specific for the detection of Salmonella spp. and Salmonella typhimurium, respectively. In this study 8.3% and 1.6% of poultry carcasses were found to be contaminated with Salmonella spp and Salmonella typhimurium respectively. In order to provide a more accurate profile of the prevalence of Salmonella spp and Salmonella typhimurium in broiler carcasses, it is pertinent to use multiplex -PCR method that could be considered as an appropriate alternative to conventional culture method.

https://ijvm.ut.ac.ir/article_19608_9460ec87a65d9ff9a03ffc0e6c1a59c8.pdf

Identification of Salmonella spp. and Salmonella typhimurium by a multiplex PCR-based assay from poultry carcasses in Mashhad- Iran

In this study, a total of 250 eggs were collected randomly from 50 retail stores in Mashhad city over a period of 3 months in the summer of 2008. Five samples from each store were collected, and transferred to the laboratory. In order to isolate Salmonella spp., conventional culture method – including pre-enrichment, enrichment, selective plating and differential plating – were performed. To confirm the identification of isolated colonies as Salmonella spp. and determining serovars as Typhimurium and Enteritidis serovars, a multiplex polymerase chain reaction assay using three pairs of primers were employed: S141 and S139 for the invA gene, specific for the genus of Salmonella; Fli15 and Tym for the fliC gene, specific for Typhimurium serovar; and Prot6e-5 and Prot6e-6 for Prot6E gene, specific for Enteritidis serovar. Four out of 250 samples (1.6%) from eggshells were determined as contaminated with Salmonella spp. Isolated colonies were confirmed as Salmonella, and their serovar was determined as Typhimurium. Salmonella spp. was not isolated from the eggs' contents.

PRACTICAL APPLICATIONS
It seems that Salmonella Typhimurium is the most prevalent serotype of egg contaminant in the Mashhad area of Iran, and the multiplex polymerase chain reaction method based on amplification from conserved genes could be a reliable alternative for conventional culture methods.

Isolation and identification of salmonella enteritidis and salmonella typhimurium from the eggs of retail stores in mashhad, iran using conventional culture method and multiplex pcr assay

Listeria monocytogenes is one of the most common foodborne pathogens. Poultry meat and products are of the main vehicles of pathogenic strains of L. monocytogenes for human. Poultry products are part of the regular diet of people and, due to nutrient content, more content of protein, and less content of fat, gain more attention. In comparison with red meat, poultry meat is more economical. So, it had a greater rate of consumption especially in barbecue form in which the growth of bacterium is favored. Subtyping of L. monocytogenes isolates is essential for epidemiological investigation and for identification of the source of contamination. In the following review, the main facet of presence of L. monocytogenes in poultry will be discussed. Most pathogenic serotypes of L. monocytogenes were detected in different products of poultry meat. Unfortunately, these isolated pathogens had sometimes resistance to commonly used antibiotics which were used for treatment of human infection.

/pdf/significance-and-characteristics-of-listeria-monocytogenes-45fp9ckuo3.pdf

Significance and Characteristics of Listeria monocytogenes in Poultry Products

The purpose of this preliminary study was to determine the prevalence of raw milk contamination with Listeria monocytogenes. In this study, 100 bulk tank milk samples were collected randomly and delivered to Pegah Pasteurization Factory in Mashhad. For isolation and identification of L. monocytogenes, the samples were first enriched using cold enrichment method in Listeria enrichment broth, followed by plating onto supplemented Oxford agar. For final identification of suspected colonies a multiplex-PCR assay, using two pair of primers was employed. The prs primers are specific for putative phophoribosyl pyrophosphate synthetase (prs) gene of Listeria spp. and the LM lip1 primers are specific for prf A gene of its monocytogenes serovar. Using this method, the contamination of raw milk with L. monocytogenes was determined to be 4% and the sensitivity of the primers was 3.5 × 10 3 cfu ml -1 , and the specificity was determined to be 100%. Considering the high specificity and sensitivity of the employed multiplex-PCR assay, it is recommended to use this method for the identification of suspected colonies of Listeria spp. and L. monocytogenes.

/pdf/the-presence-of-listeria-monocytogenes-in-raw-milk-samples-106sei5dt4.pdf

The presence of Listeria monocytogenes in raw milk samples in Mashhad, Iran

Background and Objectives: Salmonellosis caused by Salmonella spp. is one of the most important zoonotic diseases and transmits to human through raw food animal products including poultry meat. Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium are the most important strains that infect human. This study was conducted to evaluate the contamination rate of poultry carcasses with S. Enteritidis and S. Typhimurium using multiplex PCR assay. Materials and Methods: 100 samples were selected during the summer and fall of 2010 by cluster sampling method from 10 broiler flocks, which were slaughtered in a poultry abattoir located in Mashhad suburb. After culturing the samples in enrichment and selective media and obtaining suspected colonies, DNA was extracted and Salmonella isolates were identified by multiplex-PCR. Three sets of primer pairs tagreting invA gene for Salmonella genus, prot6 gene for entritidis serovar and ﬂiC gene for Typhimurium serovar were used. Results: The contamination of poultry carcasses with Salmonella was 14% (14/100) which 43% (6/14) of them were identified as S. Enteritidis and 36% (5/14) identified as S. Typhimurium, respectively. Conclusion: Results of this study indicated that the risk of zoonotic diseases created by S. Enteritidis and S. Typhimurium is relatively high in poultry carcasses.

/pdf/salmonella-enteritidis-and-salmonella-typhimorium-kqs6wy7p6g.pdf

Abdollah Jamshidi

Papers

Identification of Salmonella spp. and Salmonella typhimurium by a multiplex PCR-based assay from poultry carcasses in Mashhad- Iran

Isolation and identification of salmonella enteritidis and salmonella typhimurium from the eggs of retail stores in mashhad, iran using conventional culture method and multiplex pcr assay

Significance and Characteristics of Listeria monocytogenes in Poultry Products

The presence of Listeria monocytogenes in raw milk samples in Mashhad, Iran

Salmonella Enteritidis and Salmonella Typhimorium identification in poultry carcasses.