Potential confounding factors in currently used antibiotic susceptibility assays for the honey bee pathogen Melissococcus plutonius
Bibliographic record
Abstract
Introduction. Melissococcus plutonius is the causative agent of European foulbrood (EFB), a disease of honey bees that is endemic in many areas of the USA. Only one antibiotic, oxytetracycline (OTC), is approved for EFB management, and there have been reports of recalcitrance. Gap Statement. Resistant strains of M. plutonius have been identified in Canada and Japan, but methodology differs between studies, making reliable comparisons difficult. Additionally, no M. plutonius isolates from the USA have yet been tested for susceptibility to OTC, despite decades of use. Aim. Here, we determine the impact of media, time and persistence on the results of commonly used growth and antibiotic resistance assays using regionally representative M. plutonius isolates. Methodology. Twelve genetically diverse isolates of M. plutonius were tested for susceptibility to OTC using previously published assays, but with variations in media and time to determine factors that may be impacting results. Results. Media composition and incubation time dramatically impact antibiotic susceptibility assays for M. plutonius , differing widely between strains, likely due to differences in OTC stability. Assays that ended when growth appeared on antibiotic-free agar showed that all strains remained susceptible to OTC with an MIC of 2–4 µg ml −1 . However, M. plutonius remains viable after OTC efficacy wanes, with some strains able to persist at room temperature for at least 3.5 years. Conclusion. To standardize antibiotic susceptibility testing for M. plutonius, we recommend the use of M110 media due to stability and speed of growth. However, all strains of M. plutonius persist on M110 beyond the window of OTC efficacy, complicating assay results and interpretation, and additional research is needed to determine the clinical implications of these findings.
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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 | 0.015 | 0.037 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".