Propidium monoazide real-time PCR amplification for viable <i>Salmonella</i> species and <i>Salmonella</i> Heidelberg in pork
Bibliographic record
Abstract
Salmonella enterica serovar Heidelberg causes foodborne infections and is a major threat to the food chain and public health. In this study, we aimed to develop a rapid molecular typing approach to identify Salmonella enterica serovar Heidelberg. Using comparative genomics, four serovar-specific gene fragments were identified, and a real-time polymerase chain reaction (PCR) combined with a propidium monoazide (PMA) pretreatment method was developed for simultaneous detection of viable Salmonella sp. (invA) and Salmonella Heidelberg (SeHA_C3258). The assay showed 100% specificity for all strains tested. The assay was able to distinguish effectively viable or dead cells with the PMA. The detection limit was 2.4 CFU/mL following 6 h of incubation in enrichment Luria–Bertani medium, and the assay could detect 1.7 × 102 CFU/mL in the presence of pork background flora. In artificially contaminated pork, real-time PCR detected inoculum levels of 1.15 CFU/25 g of pork after a 6 h enrichment. Thus, our findings indicated that this comparative genomics approach could be used to screen for serovar-specific fragments and that real-time PCR with PMA was a simple and reliable method for detecting viability of Salmonella species and Salmonella Heidelberg.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".