Clospore: A Liquid Medium for Producing High Titers of Semi-purified Spores of Clostridium difficile
Bibliographic record
Abstract
Clostridium difficile continues to cause infections in healthcare and other settings. Its spores survive well indoors and require sporicidal chemicals for infection control. However, proper testing of disinfectants is impeded due to difficulties in obtaining viable spores of high enough quality and titers to meet current regulations for sporicidal claims. A new liquid medium (Clospore) has been developed, based on a systematic review of the compositions of 20 other available media. C. difficile spores grown in the new medium and treated with a mixture of lysozyme and trypsin yielded final suspensions with > 10(9) CFU/mL of viable spores, with a purity of > 91% as tested by spore-staining and phase-contrast microscopy. The spores showed a biological decay rate of about 0.1 log10/month when dried on metal disks and stored indoors (air temperature 23 +/- 2 degrees C; relative humidity 52.76 +/- 15.08%). Heating the purified spore suspensions to 70 degrees C for 10 min to inactivate any vegetative cells showed no spore activation or inactivation. The spores could be stored for at least 14 months either refrigerated (4 degrees C) or frozen (-20 or -80 degrees C) in 50% (v/v) ethanol with virtually no loss in viability. The resistance of the enzyme-treated spores to three levels of sodium hypochlorite (1000, 3000, and 5000 ppm), using a standardized quantitative carrier test, was almost identical to that of the spores concentrated by centrifugation alone. The described procedure has been successfully applied to four standard (ATCC) and six clinical strains of C. difficile.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".