Pulsed-Field Gel Electrophoresis Study of <i>Mycobacterium abscessus</i> Isolates Previously Affected by DNA Degradation
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Bibliographic record
Abstract
DNA degradation (which results in a smear pattern) occurs with almost 50% of Mycobacterium abscessus strains during pulsed-field gel electrophoresis (PFGE). We assessed the potential benefit of using thiourea-containing buffer with M. abscessus by studying 69 isolates not previously typeable by PFGE (i.e., those with a smear pattern). Random (epidemiologically unrelated) isolates that were typeable (no smear pattern) were included as controls. Genomic DNA was digested with DraI, XbaI, and AseI. PFGE gels were run in regular gel buffer with and without 100 muM thiourea. All 69 isolates that generated smear patterns had clear band profiles when the thiourea buffer was used. These isolates were divided into only 30 patterns with DraI, 20 patterns with XbaI, and 20 patterns with AseI. The molecular profiles were all closely or possibly related, and the differences between the isolates ranged from zero to six bands. By multilocus enzyme electrophoresis (MEE), 45 of 53 smear isolates (85%) belonged to two closely related electrophoretic types. These isolates contained at least one enzyme allele seen almost exclusively in this group. Isolates without smear patterns were unaffected by thiourea and produced unrelated PFGE profiles, as well as multiple MEE types. The hsp65 and 16S rRNA gene sequences of the isolates with smear patterns were identical to those of M. abscessus type strain ATCC 19977, which had a nonsmear pattern, suggesting that this clone is a subgroup within M. abscessus. This demonstrates that the inability to type M. abscessus by PFGE is associated with a single clone of organisms.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 it