Blinded comparison of performance and cost-effectiveness of chromogenic and direct latex methods for detection of group B <i>Streptococcus,</i> with in-house PCR and LAMP as reference standards
Bibliographic record
Abstract
Background: Group B Streptococcus (GBS) testing during pregnancy and application of intrapartum prophylaxis to carriers prevents early-onset disease due to GBS in neonates. New testing methods may be more accurate and cost-effective than conventional cultures. Objective: To compare performance and cost-effectiveness of three chromogenic agars and two direct latex agglutinations after carrot-broth enrichment, using in-house polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) as reference standards. Methods: A total of 285 consecutive vaginal–rectal swabs were enriched with carrot broth and then tested using conventional Streptococcus selective agar (SSA), ChromAGAR Strep B (Colourex; Alere ULC, Ontario), ChromID Strepto B (bioMérieux Canada, Quebec), Brilliance GBS (Oxoid Company Inc, Ontario) and two latex agglutination kits: PathoDxtra Strep Grouping Reagent Kit (Thermofisher Scientific, Oxoid Company, Ontario) and MEDStrep (Alere ULC, Ontario). In-house PCR and LAMP reference methods were performed on frozen carrot broth. Results: Of the 285 samples received, 244 were analyzed by in-house PCR and 195 by LAMP. The conventional method (SSA) is less sensitive than PCR, but equally specific. Chromogenic agars were as sensitive as or more sensitive than SSA, and cost as much as or more than SSA. Direct latex antigens were less sensitive and specific than SSA, and cost less than SSA. In-house PCR was more sensitive than LAMP. Conclusion: Chromogenic media perform approximately as well as the conventional method (SSA) but are costlier. Direct latex agglutination methods do not achieve adequate performance. The ideal limit of detection for PCR is unknown, since the risk to the newborn of maternal carriage of a low inoculum of GBS is unknown.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.007 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".