Effect of Molecules Secreted by <i>Lactobacillus acidophilus</i> Strain La-5 on <i>Escherichia coli</i> O157:H7 Colonization
Bibliographic record
Abstract
The probiotic bacterium Lactobacillus acidophilus strain La-5 is a gut-colonizing microorganism that, when established, becomes an important part of the gastrointestinal (GI) tract microbiota. It has been shown to be effective against enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection. We have previously shown that molecules released by probiotic strain La-5 influence the transcription of EHEC genes involved in colonization and quorum sensing. In this work, we report on the ability of these molecules to prevent the adherence of EHEC to epithelial cells and on its capacity to concentrate F-actin at adhesion sites. With a fluorescein-labeled phallotoxin, it was shown that La-5 cell-free spent medium (CFSM) fractions remarkably reduced attaching and effacing lesions in HeLa cells. We also observed a significant inhibition of bacterial adhesion to Hep-2 cells when they were treated with the same La-5 CFSM fractions. In order to observe if La-5 CFSM fractions exhibited the same effect in vivo, we studied the ability of luminescent EHEC constructs (LEE1::luxCDABE) to adhere to intestinal epithelial cells of specific-pathogen-free ICR mice following intragastric inoculation. Colonization of the GI tract by luminescent EHEC O157:H7 was monitored in real time with a slow-scan charge-coupled device camera. At the same time, fecal shedding of EHEC was studied. Following oral gavage of the La-5 active fraction, we observed a reduced amount of bioluminescence signal along with a decrease in fecal shedding by mice, indicating an effect on the ability of the organism to colonize the GI tract. Our results confirm past evidence of the possibility of blocking or interfering with EHEC's virulence by active molecules contained in the probiotic CFSM and identify novel therapeutic alternatives to antibiotic treatments in the fight against food-borne pathogens.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".