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Gewählte Master / Diploma Thesis:

Ulla Bernkopf (2017): Bacterial background flora in the detection of food-associated Yersinia.
Master / Diploma Thesis - Institut für Lebensmittelwissenschaften, BOKU-Universität für Bodenkultur, pp 126. UB BOKU obvsg

Data Source: ZID Abstracts
Enteropathogenic Yersinia spp. were ranked as the third most commonly reported cause of zoonosis in the EU in 2015 (EFSA and ECDC, 2016). The standard method for the detection of presumptive pathogenic Yersinia enterocolitica in food products is the cultivation-based EN ISO 10273:2003. However, the scientific community agrees that the current reference technique does is suboptimal. Pathogenic Yersinia spp. are initially present in low numbers in food products and have to be enriched prior to detection. However, also food-associated bacteria are co-enriched and negatively influence the detection probability of Yersinia species. Moreover, discrimination of Yersinia spp. from other bacterial species with similar colony morphologies is challenging. Therefore, knowledge about the food-assocociated bacterial flora is essential to allow improvements in the detection of Yersinia spp. from different food products. In the course of this study universal (TSB) and selective (PSB, ITC) enrichment of native and artificially contaminated raw milk and pork loin samples was carried out, followed by selective plating on CIN and SSDC agar. The cultivable background community was identified by colony PCR and 16S rDNA sequencing. This study shows the diversity of the co-enriched food microflora and indicates some potential candidates having an inhibitory effect on growth and detection of pathogenic Yersinia spp. Frequently isolated native bacteria were identified as species of the genera Pseudomonas, Citrobacter and Serratia. Based on the results, the identified microflora is specific for each food sample. The recovery of spiked Yersinia spp. was better from pork loin than from raw milk samples. Spiked Yersinia could not be detected in raw milk. These results demonstrate that the EN ISO 10273:2003 reference method is not optimal and that indeed detection efficiency of Yersinia enterocolitica and Y. pseudotuberculosis might be affected by the native bacterial background flora in food.

Beurteilende(r): Domig Konrad

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