Increased tolerance of<i>Staphylococcus aureus</i>to vancomycin in viscous media
Bibliographic record
Abstract
The increased viscosity observed in biofilms, adherent communities of bacterial cells embedded in a polymeric matrix, was hypothesized to induce increased tolerance of bacteria to antibiotics. To test this concept, planktonic Staphylococcus aureus cells were grown and exposed to vancomycin in media brought to specific viscosities in order to mimic the biofilm extracellular polymeric matrix. A viscous environment was observed to decrease the vancomycin susceptibility of planktonic S. aureus to levels seen for biofilms. Both planktonic S. aureus at a viscosity of 100 mPa s and staphylococcal biofilms were able to survive at >500 times the levels of the antibiotic effective against planktonic populations in standard medium. Time-dependent and dose-dependent viability curves revealed that more than one mechanism was involved in high S. aureus tolerance to vancomycin in viscous media. Increased viscosity affects antibiotic susceptibility by reducing diffusion and the mass transfer rate; this mechanism alone, however, cannot explain the increased tolerance demonstrated by S. aureus in viscous media, suggesting that viscosity may also alter the phenotype of the planktonic bacteria to one more resistant to antimicrobials, as seen in biofilms. However, these latter changes are not yet understood and will require further study.
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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".