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- Thisted Lambertz, Susanne, et al.
(författare)
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Evaluation of a combined culture and PCR method (NMKL-163A) for detection of presumptive pathogenic Yersinia enterolitica in pork products
- 2007
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Ingår i: Journal of Food Protection. - : International Association for Food Protection. - 0362-028X .- 1944-9097. ; 70:2, s. 335-340
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Tidskriftsartikel (refereegranskat)abstract
- A combined culture and PCR method for detection of pathogenic Yersinia enterocolitica in food (NMKL-163A) was evaluated by testing samples of artificially and naturally contaminated pork. The performance of the pre-PCR sample treatment, buoyant density centrifugation, was first compared with two commercially available methods (DNeasy tissue kit and PrepMan). We found that similar sensitivity was reached (i.e., 25 CFU/g of food was detected by single PCR) with the buoyant density centrifugation and the DNeasy Tissue kit when tested on overnight enrichments. However, the DNeasy tissue kit was superior when tested on nonenriched homogenates; the detection limit was 25 CFU/g in minced beef by single PCR and 25 CFU/g in sausage by nested PCR. We then analyzed 100 raw minced pork samples. Thirty-five tested positive for presumptive pathogenic Y. enterocolitica when analyzed by the NMKL-163A method, whereas none tested positive when analyzed in parallel by a standard culture method (ISO 10273). We also analyzed 97 samples of cold-smoked pork sausage, of which approximately 11% tested positive by the NMKL-163A method. This study showed that sensitivities such as those obtained by nested PCR were required for detection of the pathogen in naturally contaminated samples, and therefore the nested PCR primers, which are included in the NMKL-163A method only as an option, need to be validated and applied routinely.
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| 2. |
- Thisted Lambertz, Susanne, et al.
(författare)
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Identification and characterization of pathogenic Yersinia enterocolitica isolates by PCR and pulse-field get electrophoresis
- 2005
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Ingår i: Applied and Environmental Microbiology. - Washington, USA : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 71:7, s. 3674-3681
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Tidskriftsartikel (refereegranskat)abstract
- Approximately 550 to 600 yersiniosis patients are reported annually in Sweden. Although pigs are thought to be the main reservoir of food-borne pathogenic Yersinia enterocolitica, the role of pork meat as a vehicle for transmission to humans is still unclear. Pork meat collected from refrigerators and local shops frequented by yersiniosis patients (n = 48) were examined for the presence of pathogenic Yersinia spp. A combined culture and PCR method was used for detection, and a multiplex PCR was developed and evaluated as a tool for efficient identification of pathogenic food and patient isolates. The results obtained with the multiplex PCR were compared to phenotypic test results and confirmed by pulsed-field gel electrophoresis (PFGE). In all, 118 pork products (91 raw and 27 ready-to-eat) were collected. Pathogenic Yersinia spp. were detected by PCR in 10% (9 of 91) of the raw pork samples (loin of pork, fillet of pork, pork chop, ham, and minced meat) but in none of the ready-to-eat products. Isolates of Y. enterocolitica bioserotype 4/O:3 were recovered from six of the PCR-positive raw pork samples; all harbored the virulence plasmid. All isolates were recovered from food collected in shops and, thus, none were from the patients' home. When subjected to PFGE, the six isolates displayed four different NotI profiles. The same four NotI profiles were also present among isolates recovered from the yersiniosis patients. The application of a multiplex PCR was shown to be an efficient tool for identification of pathogenic Y. enterocolitica isolates in naturally contaminated raw pork.
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