Pyrosequencing Assay to Rapidly Detect Clarithromycin Resistance Mutations in Canadian<i>Helicobacter pylori</i>Isolates
Bibliographic record
Abstract
BACKGROUND: Mutations at positions 2142 or 2143 in the twocopy 23S ribosomal RNA gene of Helicobacter pylori are highly predictive of in vitro clarithromycin resistance and failure of clarithromycin-containing treatment regimens. OBJECTIVE: To design an assay to rapidly detect these mutations using rapid polymerase chain reaction and pyrosequencing, a novel method of 'sequencing by synthesis', and to test this assay with a collection of Canadian H pylori isolates. METHODS: Forty-two H pylori isolates (24 clarithromycin-resistant, 18 clarithromycin-susceptible) were studied. A target region in the 23S gene was rapidly amplified and sequenced by pyrosequencing. RESULTS: Mutations at one of the two positions studied were present in 20 of the 24 (83%) clarithromycin-resistant isolates; 13 had double- copy A2143G mutations, four had double-copy A2142G mutations and three had single-copy A2143G mutations. There were no mutations in 17 of the 18 (94%) susceptible isolates. A single-copy A2142G mutation was detected in one susceptible isolate. CONCLUSIONS: The pyrosequencing assay developed was able to detect and differentiate mutations at positions 2142 and 2143 in either one or both copies of the H pylori 23S ribosdomal RNA gene. Further study is needed to determine whether this pyrosequencing assay can be used to determine H pylori susceptibility to clarithromycin from clinical specimens such as stools or gastric biopsies.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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".