ANTIMICROBIAL RESISTANCE AND GENOMIC CHARACTERIZATION OF NORTH AMERICAN MELISSOCOCCUS PLUTONIUS ISOLATES
Notice bibliographique
Résumé
European foulbrood (EFB) is a disease of honey bee larvae caused by Melissococcus plutonius. Western Canada has seen a recent emergence of EFB disease despite oxytetracycline (OTC) use, resulting in economic losses for beekeepers. In North America, antimicrobials are widely used for treatment and control of bacterial brood diseases, including both American foulbrood (AFB) and European foulbrood (EFB) disease. In contrast, prophylactic antimicrobial-use is prohibited in beekeeping in the European Union. Thus, antimicrobial resistance (AMR) poses an imminent threat to North American apiaries, especially for cases of EFB disease since only a single antibiotic, oxytetracycline (OTC), is approved for use. In contrast, tylosin (TYL) and lincomycin (LMC) are also registered for use against AFB. The most recently published antibiotic sensitivity testing for M. plutonius was performed approximately 20 years ago on M. plutonius isolates from outside North America. Moreover, little is known about the resistance profiles of M. plutonius and how these are related to the efficacy and ability of drugs to clear infection in honey bee larvae. To address these issues, we sought to investigate OTC, TYL, and LMC as potential treatment options for EFB disease using laboratory-reared larvae infected with M. plutonius. Moreover, our study aims to determine if antibiotic resistance to OTC TYL, or LMC exists in North American M. plutonius isolates. Genomic characterization of Canadian isolates is lacking as well, and thus we also aimed to characterize a subset of isolates we did antimicrobial susceptibility testing for. Firstly, the utility of OTC, TYL, and LMC were compared through an experimental design that either mimicked Metaphylaxis or antimicrobial intervention, using concentrations that corresponded to previous studies. We found that all concentrations prevented clinical signs of EFB disease following infection with M. plutonius 2019BC1 in vitro. Interestingly, M. plutonius 2019BC1, following antimicrobial susceptibility testing was characterized as resistant to OTC, with a minimum inhibitory concentration (MIC) of 32 µg/mL. Accordingly, we then compared the utility of the three drugs using four M. plutonius isolates that demonstrated a range of resistance phenotypes. Additionally, treatment doses were determined through corresponding MICs. We demonstrate that infections and the efficacy of antimicrobial treatments in honey bee larva are concordant with in vitro MIC measurements and that the survival outcomes of larva are not dependent on M. plutonius clearance but a strain-dependent reduction of their numbers within larva. To assess the range of antimicrobial resistance present in North America, a total of 67 M. plutonius isolates. We found that a majority of isolates had a minimum inhibitory concentration that indicated resistance to OTC (> 16 μg/mL), while all isolates had MICs that corresponded to sensitivity against tylosin and lincomycin (< 4 μg/mL). Interestingly, resistant isolates showed sensitivity to OTC when different media was used, indicating that resistance is media-dependent. 53 of these isolates were used for whole genome sequencing and genomic comparison with 17 publicly available M. plutonius genomes. Through genomic characterization, we did not identify a resistance gene to explain the resistance seen for OTC. Moreover, phylogenetic analysis demonstrated that OTC resistance was not clustered together. However, similar clonal complexes cluster together.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,001 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».