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  • Author: Kinga Wieczorek x
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Abstract

A total of 1229 samples, including 406 bovine hides and 406 corresponding carcasses at the slaughter level, as well as 417 beef meat from local supermarkets, were tested for the presence of Salmonella sp. Eighteen (1.5%) samples were positive for the target microorganism, and the highest prevalence (2.2%) was found in meat, followed by carcasses (1.2%) and hides (1.0%). Among the isolated strains, Salmonella enterica serotypes Enteritidis (six isolates) and Schleissheim (six strains), followed by Dublin (four contaminated samples) were the most predominant. The antimicrobial resistance analysis against nine antimicrobials with the MIC technique revealed that most isolates were sensitive to all antibacterial agents. However, one S. Typhimurium of carcass origin was multidrug resistant, and displayed the resistance to four antimicrobials, i.e. ampicillin, streptomycin, tetracycline, and sulphametoxazole. Furthermore, one S. Enteritidis (from carcasses), two S. Dublin (of beef origin), and one S. London (from meat) strains were resistant to sulphametoxazole. The restriction enzyme analysis with XbaI resulted in eight different PFGE types. The obtained results suggest that cattle may be an underestimated source of pathogenic Salmonella for consumers.

Abstract

A total of 2668 swabs from poultry (n = 2166), pig (n = 311), and cattle (n = 191) carcasses were collected in slaughterhouses all over Poland and tested for the presence of Campylobacter. It was found that 1319 (49.4%) of them were contaminated with these bacteria. The percentages of the positive samples were different in each year of the study and the highest proportion of Campylobacter contaminated samples occurred in 2009, when 64.1% of investigated carcasses were positive. On the other hand, the lowest prevalence of Campylobacter was observed in 2013, in the last year of the survey. In all kind of carcass samples both C. jejuni and C. coli were identified, although the pork meat was more contaminated with C. coli (75.3% of positive samples) than with C. jejuni (24.7%), whereas poultry was nearly equally positive for C. jejuni and C. coli (50.6% and 49.4% respectively). The analysis of seasonal contamination of the carcasses revealed that more positive results were found during the second half of year than between January and June. The prevalence of Campylobacter showed that in all provinces, except one (Pomorskie), the mean percentage of the positive samples was above 40%. The most contaminated samples were identified in Lubelskie (69.3%) and Zachodniopomorskie (66.3%) regions. The obtained results showed that slaughtered animals in Poland, especially broilers, were often contaminated with Campylobacter, either C. jejuni or C. coli.

Removal of carbonaceous matters over alumina supported chromium and platinum chromium catalysts

Platinum, both alone and with a low and high amount of chromium as an additive supported on alumina, was studied as a catalyst. These catalysts were examined in the removal of the carbonizate as a model material. It was found that the 2Cr/Al2O3 catalyst showed a significant increase in the catalytic activity as compared to 20Cr/Al2O3. An addition of platinum was found to cause a decrease of activity.

Abstract

Introduction: Campylobacter jejuni is one of the most frequently reported causes of foodborne bacterial enteric disease worldwide. The main source of these microorganisms is contaminated food, especially of poultry origin. There are several molecular methods for differentiation of Campylobacter isolates at the subgenus level, and one of these is porA-typing based on the sequencing of the major outer-membrane protein (MOMP) encoding gene. The aim of the study was to test the molecular relationship of C. jejuni strains isolated at different points along the poultry food chain and assess the population structure of the isolates.

Material and Methods: A total of 451 C. jejuni were used in the study, and a DNA fragment of 630 bp of the MOMP encoding gene was amplified and sequenced.

Results: One hundred and ten sequence types were identified, with 69 (62.7%) unique to the isolates' origin and 30 not present in the database. The most prevalent nucleotide variant 1 was detected in 37 (8.2%) strains. These isolates were identified in all poultry sources tested, especially in faeces (15 isolates) but also in poultry carcasses and meat (11 isolates in each).

Conclusion: The porA typing method was highly discriminative for C. jejuni of poultry origin since the Simpson's diversity index (D) achieved a value of 0.876, indicating considerable diversity in the bacterial population tested. The method may be further used for epidemiological investigation purposes.

Abstract

In 2015 in the European Union member states listeriosis caused 270 deaths. Food is the route of transmission in 99% of all human infection cases. Several studies from different countries have shown that the presence of Listeria monocytogenes in food can be as high as 58.3%. One of the most important ways to protect food from these microorganisms is to prevent the spread of the bacteria at processing plants at different stages of food production chain. The ability of L. monocytogenes to survive in extreme conditions and to form biofilms on various surfaces is a significant challenge for food safety. Removal of these bacteria from niches in processing plants is difficult and requires the use of sanitisers and precise equipment cleaning. The presence of L. monocytogenes in processing environment at slaughterhouses, deli meat factories or in retail may be a reason of cross-contamination. Proper hygienic systems applied by workers in food preparing places and knowledge about different routes of spreading of these bacteria may effectively decrease the risk of food contamination. Standardised legal regulations and control of meat product manufacture should be a fundamental way to protect food from L. monocytogenes contamination.

Abstract

Introduction: The study objective was to develop and evaluate a new TaqMan multiplex real-time PCR method for Salmonella, L. monocytogenes, and verotoxigenic Escherichia coli (VTEC) detection in slaughtered animal carcasses.

Material and Methods: The procedure included an enrichment step, DNA extraction, and two multiplex real-time PCRs. The first PCR detected the invA and hly genes of Salmonella and L. monocytogenes respectively, the second the vtx1, vtx2, and eae genes of VTEC.

Results: The validation of this method resulted in 100% relative sensitivity, specificity, and accuracy as compared to the reference ISO methods. The limit of detection per swab sample was established at 1 cfu for Salmonella and L. monocytogenes and 2 cfu for VTEC. The authors analysed 265 slaughterhouse-collected swabs from cattle, pig, and poultry carcasses. Among 125 from cattle, 51 were positive for VTEC, 29 for Salmonella, and 1 for L. monocytogenes. Among swabs from pig carcasses (n = 95), three, two, and one sample were positive for these pathogens respectively. None of the microorganisms tested for was identified in 45 samples of poultry origin.

Conclusion: The obtained results showed that the method developed can rapidly identify the main bacterial pathogens that may contaminate carcasses of food-producing animals.

Abstract

A total of 135 L. monocytogenes strains isolated from slaughtered cattle and beef meat were tested by the pulsed field gel electrophoresis (PFGE). The AscI restriction analysis revealed a genetic heterogeneity among investigated isolates since 31, 9, and 35 profiles were distinguished among hide, carcass, and meat strains, respectively. The PFGE profiles of the isolates were also analysed in relation to serotypes, virulence genes, and antimicrobial resistance. It was shown that strains displaying the same PFGE type were of the same serotype while correlation between pulsotype and antimicrobial resistance was poor. The obtained results suggest that a cross-contamination between bovine hides and carcasses may occur during the slaughter process. Moreover, identification of identical PFGE types among L. monocytogenes found during a study period may suggest a common source of contamination or presence of persistent strains able to survive for a long time. These results emphasise the importance of molecular subtyping methods, including PFGE, in monitoring and tracking pathogen contamination along food chain.