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Yersinia enterocolitica detection in pork products: Evaluation of isolation protocols
M F Peruzy1, M Aponte2, Y T R Proroga3
1Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium; Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Via Delpino 1, 80137, Naples, Italy; Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Karel Lodewijk Ledeganckstraat 35, Ghent, Belgium.
Abstract:
Conventional methods for Yersinia enterocolitica detection in food samples are generally considered inadequate. Problems arise from the presence of the so-called "background flora", coupled to the low contamination level of the pathogen. Since, data on the microbial ecology occurring in competitive microflora are still lacking, MALDI TOF MS was used for strains 'identification after enrichment in PSB or ITC broths, and after plating on selective CIN medium at different incubation times. SYBR Green Real time PCR was used for the Y. enterocolitica strains' detection (4/O:3, 1A/O:5) in experimentally contaminated foods, as well as in naturally contaminated samples. A higher number of different bacterial genera (10 on CIN and 18 on PCA) was recorded after enrichment in PSB, whilst enrichment in ITC led to recovery of 6 and 10 genera on CIN and PCA, respectively. Yersiniaceae was the dominant family on the first day of incubation, but on the second day the percentage of isolation considerably decreased. By testing experimentally contaminated samples, substantial difficulties were encountered. The biotype 1A was always detected, whereas strain 4/O:3 proved to be poorly competitive. Based on the data, the enrichment media PSB and ITC, currently proposed for Y. enterocolitica detection, need to be improved to promote a successful pathogen's recovery.
Insights
Detecting Yersinia enterocolitica in food is challenging due to background flora and low contamination. Current enrichment methods (PSB, ITC) need improvement for better pathogen recovery and accurate detection.
Area of Science:
- Food Microbiology
- Bacterial Pathogen Detection
- Microbial Ecology
Background:
- Conventional Yersinia enterocolitica detection methods in food are often inadequate.
- Challenges include high levels of background flora and low pathogen contamination.
- Limited data exists on the microbial ecology of competitive microflora during detection.
Purpose of the Study:
- To evaluate the effectiveness of enrichment broths (PSB, ITC) and selective media (CIN) for Yersinia enterocolitica detection.
- To assess the impact of microbial ecology on pathogen recovery.
- To identify limitations in current detection protocols.
Main Methods:
- Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) for strain identification.
- SYBR Green Real-time PCR for Y. enterocolitica detection (serotypes 4/O:3, 1A/O:5).
- Analysis of bacterial genera and Yersiniaceae family dominance after enrichment and plating on selective media.
Main Results:
- Enrichment in PSB broth yielded more bacterial genera compared to ITC broth.
- Yersiniaceae family dominance decreased significantly after the first day of incubation.
- Real-time PCR detected biotype 1A consistently, but strain 4/O:3 showed poor competitiveness in experimentally contaminated food samples.
Conclusions:
- Current enrichment media (PSB, ITC) require optimization to enhance Yersinia enterocolitica recovery.
- The competitive microflora significantly impacts pathogen detection success.
- Improved enrichment strategies are necessary for reliable detection of Y. enterocolitica in food.
