جستجوی مقالات مرتبط با کلیدواژه "سالمونلا" در نشریات گروه "صنایع غذایی"

Nowadays, the occurrence of antibiotic-resistant bacterial strains in food is increasing, which makes antibiotic treatment of infected food more difficult. One of the food sources that can cause foodborne infection is dairy products made from raw milk and one of the bacteria resistant to various antibiotics is Salmonella. The aim of this study was to investigate the presence of antibiotic-resistant Salmonella species in Poosti and Koozeh cheeses produced from raw milk in western Iran. For this purpose, the probable Salmonella species were isolated in Koozeh cheese from Bukan and Poosti cheese from Lorestan and Kermanshah. After initial phenotypic identification and biochemical testing, molecular identification was performed by amplification of the 16S rRNA gene with primers U1492R and B27F. The isolates were tested for resistance to tetracycline, oxacillin, penicillin and ampicillin. The results confirmed the presence of Salmonella enterica subspecies Typhimurium in all three cheeses among 14 Enterococcus isolates. The species of all three cheese were resistant to oxacillin, penicillin and ampicillin and the identified species of Lorestan Poosti cheese were resistant to tetracycline. But the identified species in Kermanshah Poosti cheese and Bukan Koozeh cheese were sensitive to tetracycline. The results of this study indicate that local Poosti and Koozeh cheeses in some western parts of the country may be carriers of antibiotic-resistant Salmonella strains and that in case of microbial infection caused by contaminated cheese, treatment with antibiotics may be difficult.

Poultry and meat products are the largest sources of non-typhoid salmonella infections in most countries. Studies have shown that raw foods of animal origin, especially poultry and its products, are the main source of contamination of kitchens and restaurants. In terms of growth conditions, these microorganisms are resilient bacteria and easily adapt to their environmental conditions. Salmonella has been known to cause intestinal disease for many years and has been reported as the most important cause of food poisoning. According to Iranian and international standards, there should be no S. enteritidis or S. typhimurium in 25 grams of food. DNA-based methods for the identification and differentiation of Salmonella serovars have been designed and applied using specific primers at the genus and serovar levels. Therefore, they can be used as useful and rapid screening tests, as well as to supplement or replace conventional biochemical and serological tests. Real-time PCR, with the most accurate and reliable results using a fluorescence probe, which of course has a high cost. In this method, sequence specific fluorescence probes are used, and as a result, in the target molecule, screening and determination the presence or even the concentration of specific sequences is possible. Therefore, even in the presence of other types of nucleic acid molecules, the results are obtained quickly and have a high level of specificity. Under these conditions, if specific probes with different florescence dyes are used, even multiple targets can be detected in a single PCR reaction. The aim of this study was to identify S. enteritidis or S. typhimurium by PCR and Salmonella spp. by real time PCR method in poultry products. 

In total, 45 samples of poultry products, including chicken breast, liver and gizzard (15 samples each) were purchased from different regions of Mashhad and from various companies and transferred to the laboratory in accordance with hygienic standards. For each sample, 25 g of tissue was isolated and homogenized under sterile conditions and DNA extraction was then performed using a DNA extraction kit. The extracted DNA was evaluated by agarose gel electrophoresis. The purity and quantity of DNA extracted from each sample was examined by spectrophotometry method. In the next step, in order to identify the genus Salmonella, the samples were examined by real time PCR. In this method we used an internal control to ensure that negative results are not false negative due to inhibitors. The results of real time PCR showed that out of 45 samples, nine samples were infected with Salmonella. Then, these nine samples were evaluated for Salmonella typhimurium and Salmonella enteritidis infection by conventional PCR method. 

The results showed that out of nine samples that were positive in real time PCR test, seven samples were contaminated with Salmonella typhimurium, of which five samples were related to chicken breast and two to liver. Regarding Salmonella enteritidis infection, out of nine samples, only one sample was contaminated, which was related to chicken breast. Conventional methods have been traditionally used to enumerate target bacteria in food. However, these methods have some limitations and require considerable time and labor. Previous studies have already shown that real time PCR is more effective than conventional bacteriological methods for the detection of Salmonella spp. In a study by Whyte et al. (2002) The presence of Salmonella was assessed by traditional culture methods and by a Salmonella-specific polymerase chain reaction (PCR) test. Salmonella was recovered from 16% of samples using traditional culture methods. In contrast, the PCR assay proved to be more sensitive and detected Salmonella DNA in 19% of the examined samples (Whyte et al. 2002). Results of PCR with specific primers showed that reactions in real time PCR with general primers of Salmonella spp. were done correctly. Despite of accuracy and speed of real time PCR to detect DNA of microorganisms, further studies are developed to have more advantages. Loop-mediated isothermal amplification (LAMP) showed a higher sensitivity of Salmonella detection in compare to qPCR (Vichaibun & Kanchanaphum, 2020). Although LAMP could detect trace amount of Salmonella DNA but primer design for this reaction is very difficult. However, it is important to highlight that non-viable cells can be detected by real time PCR or other DNA-based methods, which does not occur in traditional methods of culture and isolation that require viable cells for quantification (Zeng et al., 2016).

Salmonella spp. and Campylobacter can be transmitted through raw milk and cause foodborne illness. The aim of this study was to investigate the prevalence of Campylobacter and pathogenic species of Salmonella spp. species in raw cow's milk using molecular method in Mazandaran province. 100 samples of raw milk were randomly collected from traditional milk collection and retail centers in Mazandaran province in 2019. All samples were transferred as soon as possible to the microbiology laboratory of the Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, in sterile containers and in suitable cold chain conditions. DNA was extracted from milk samples using a commercial kit and then the polymerase chain reaction was performed using appropriate primers to identify Campylobacter jejuni, Campylobacter coli and Salmonella. Out of 100 samples, 7 samples (7%) were infected with Campylobacter jejuni, no positive sample of Campylobacter coli was observed and 2 samples (2%) were infected with Salmonella. According to the results of the present study and the presence of the mentioned bacteria in milk, it is necessary to observe the hygienic principles in the dairy industry, processing and use of sufficient heat to eliminate the mentioned bacteria in raw milk and also use fast and accurate methods to identify These bacteria.

Ozone is a strong oxidant and a potent disinfecting agent. There are numerous application areas of ozone in food industry. While there are many investigations on the application of ozone in food industry, relatively little information is available on the potential of ozone to reduce microbial populations in fresh-cut fruits and vegetables and the visual quality of lettuce. In this study, ozone water was applied at five concentrations (0.6, 0.8, 1.2, 1.6 and 2 ppm) for four exposure times (1, 3, 5 and 10 min) on natural microflora and E. coli O157:H7 and Salmonella inoculated of lettuce. The reduction in the total bacterial count, yeast and mold, total coliform, as well as lactic acid bacteria counts were examined. The promising results indicated the efficacy of ozone water to reduce the microbial populations on lettuce. In the best condition, the inoculated samples of E. coli O157:H7 (ATCC 35150, NCTC 12900), Salmonella typhi morium (ATCC 14028, NCTC 12023) and Salmonella enterica subsp, enterica (PTCC 1709) on lettuce were decreased further than 2 log10 cfu/g. The results showed the population of aerobic mesophilic bacteria, yeast/ moulds, total coliforms and lactic acid bacteria were decreased to 1.54, 0.94, 1.94 and 1.35 log10 cfu/g respectively. The method of ozone generation, type of application, as well as the optimal exposure time and concentration of ozone as an antimicrobial agent on lettuce is mentioned in detail.

Food –borne diseases are important public health problems in the world. In recent years significant increase in the incidence of Salmonellas has been reported by WHO. Because Salmonellas resistance to antibiotics. The present study is to evaluate the prevalence of Salmonella in trails chicken meats in Tehran. Between Bahman 2004 to Aban 2005 we analyzed 198 samples of chicken meats in Tehran city. Each sample weighing approximately 800 g was collected. Salmonellas was isolated from 93 of the samples analyzed (47%). The predominant serotypes were S. Enteritis (48. 4%)، S. Hadar (26. 9%) and B4 22. 3%). Otherserotypes such as S. Derby and Paratyphoid B were in much lower levels.

Aerobic mesophilic counts (AMC)، were obtained by swabbing 25 cm2 areas at seven site (neck، brisket، leg، flank، rib set، forehand، hind quarter) on beef carcasses، after each Slaughter process (skinning، evisceration، splitting، trimming and primary washing، final washing). Reduction in counts at individual sites were observed after trimming and primary washing (about 0. 2 log cfu. cm-2) and final washing (about 0. 2 log cfu. cm-2) similarly. Increases in counts at most outside sites were observed after skinning، (about 2. 5 - 3. 5 log cfu. cm-2) and after evisceration، at brisket (about 1 log cfu. cm-2) and forehand (about 0. 5 log cfu. cm-2) respectively. The incidence of Salmonella and E. coli on beef carcasses were also obtained by swabbing the outside surfaces of 12 carcasses after each stage. A large number of increases in positive samples for E. coli and Salmonella was observed after skinning and after evisceration (16. 6% and 9. 2% respectively). After final washing Salmonella and E. coli were detected on 11. 9% and 7. 1% of samples. The impact of beef slaughter processes on carcass microbiology and their potential use as critical control points (CCPs) during beef production are discussed.