Hypo-osmotic stress is an anticipatory trigger of heat-resistance in presumptive extraintestinal pathogenic Escherichia coli isolated from treated sewage
Bibliographic record
Abstract
(ExPEC) are responsible for a variety of human infections (urinary tract infections, septicemia, meningitis) and can be routinely isolated from treated sewage. However, the phenotypic properties mediating treatment resistance in ExPEC remain elusive. Herein, we examined heat-resistance in presumptive wastewater ExPEC (W-ExPEC) surviving sewage chlorination or full-scale wastewater treatment. Interestingly, heat-resistance in W-ExPEC was triggered by exposure to hypo-osmotic conditions (i.e., sterile distilled water), resulting in a 10- to 1,000-fold increase in heat-resistance compared to cells exposed to iso-osmotic conditions (i.e., phosphate buffered saline). Remarkably, hypo-osmotic induction of heat resistance occurred extremely fast, in as little as 30 s, and was reversible, demonstrating the phenotypic plasticity of this stress response. Hypo-osmotic stressed W-ExPEC strains survived 58 °C temperatures for up to 20 min - this compared to the clinical reference ExPEC strain, CTF073, which became non-culturable after only 5 min of exposure at this temperature (>8 log10 decline in culturability). The upper thermotolerance level of W-ExPEC (defined as the temperature where culturability was lost after 5 min of exposure) was 62 °C, compared to 58 °C for CFT073. The finding that osmotic stress acts as an anticipatory inducer of heat resistance in W-ExPEC is novel, providing some insights into the possible mechanisms triggering a treatment resistant phenotype in W-ExPEC. The evolution of treatment resistance is worrying prospect for public health, given that waste treatment is a hallmark of infectious disease control in modern society.
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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 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".