Transferable, multiple antibiotic and mercury resistance in Atlantic Canadian isolates of Aeromonas salmonicida subsp. salmonicida is associated with carriage of an IncA/C plasmid similar to the Salmonella enterica plasmid pSN254
Bibliographic record
Abstract
OBJECTIVES: The aim of this study was to examine the molecular basis for multiple antibiotic and mercury resistance in Canadian isolates of Aeromonas salmonicida subsp. salmonicida. METHODS: Phenotypic and genotypic methods were employed to identify plasmid-associated antibiotic and mercury resistance genes and to determine the organization of those genes in multidrug-resistant (MDR) A. salmonicida isolates. RESULTS: The MDR phenotype was transferable via conjugation using Escherichia coli, Aeromonas hydrophila and Edwardseilla tarda as recipients. Antibiotic and mercury resistance genes were carried by a conjugative IncA/C plasmid. Three distinct antibiotic resistance cassettes were characterized; first a class I integron containing an aadA7 gene encoding for an aminoglycoside-3'-adenyltransferase, the second cassette showed 99.9% nucleotide sequence homology to a cassette previously identified in the Salmonella enterica IncA/C plasmid pSN254, containing floR, tetA, sulII and strA/strB sequences. The third cassette showed 100% nucleotide sequence similarity to a transposon-like element, containing a bla(CMY-2) beta-lactamase in association with sugE and blc sequences. This element is known to be widely distributed among clinical and food-borne Salmonella and other Enterobacteriaceae throughout Asia and the United States. Mercury resistance was linked to the presence of a mer operon that showed 100% nucleotide sequence homology to the mer operon carried by plasmid pSN254. CONCLUSIONS: Each MDR A. salmonicida isolate carried the same plasmid, which was related to plasmid pSN254. This is the first report of plasmid-mediated florfenicol-resistant A. salmonicida in North America. In addition, it is the first report of a plasmid-associated AmpC beta-lactamase sequence in a member of the Aeromonadaceae.
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How this classification was reachedexpand
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".