TABLE 4.
Characterization of 40 OTC-resistant, motile Aeromonas isolates with large (>30 kb) plasmids from a freshwater fish farming environment, including presumptive biochemical identification and detection of antibiotic resistance genesd
| Isolate no. | Date (mo/yr) | Source | Identification | Resistance phenotype | Tet determinant | Class 1 integrons/gene inserts | Tc status |
|---|---|---|---|---|---|---|---|
| 1-75 | 11/97 | Water/inlet | A. hydrophila | OTC, S/T | A | dhfr2a-ant(3′′)1a | + |
| 1-78 | 11/97 | Water/pond | A. hydrophila | OTC, OXA, S/T | E | NDc | |
| 1-163 | 4/98 | Rainbow trout | A. hydrophila | OTC, S/T | A | dhfr1-ant(3′′)1a-catB2 | |
| 1-231 | 6/98 | Sediment/outlet | A. hydrophila | OTC, OXA, S/T | D | ND | + |
| 1-250 | 7/98 | Rainbow trout | NIa | OTC, S/T | NCb | dhfr1-ant(3′′)1a | + |
| 1-318 | 10/98 | Sediment/pond | A. hydrophila | OTC | E | ND | |
| 1-337 | 10/98 | Water/pond | A. veronii biovar sobria | OTC, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 1-358 | 10/98 | Sediment/outlet | A. veronii biovar sobria | OTC, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 1-372 | 12/98 | Sediment/outlet | A. hydrophila | OTC, OXA, S/T | NC | ND | |
| 2-41 | 10/97 | Rainbow trout | A. bestiarum | OTC, S/T | NC | dhfr1-ant(3′′)1a | + |
| 2-62 | 11/97 | Sediment/outlet | A. hydrophila | OTC, S/T | A | dhfr2a-ant(3′′)1a | + |
| 2-85 | 1/98 | Water/pond | A. hydrophila | OTC, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 2-155 | 4/98 | Water/pond | A. hydrophila | OTC, OXA | NC | ND | + |
| 2-189 | 6/98 | Water/outlet | NI | OTC, S/T | NC | dhfr1-ant(3′′)1a | + |
| 2-197 | 6/98 | Rainbow trout | NI | OTC, S/T | NC | dhfr1-ant(3′′)1a-catB2 | |
| 2-219 | 6/98 | Rainbow trout | A. hydrophila | OTC, S/T | NC | ND | |
| 2-280 | 9/98 | Sediment/pond | A. hydrophila | OTC, S/T | A | dhfr1-ant(3′′)1a-catB2 | + |
| 2-282 | 9/98 | Sediment/outlet | A. hydrophila | OTC | NC | ND | |
| 2-321 | 9/98 | Sediment/outlet | A. hydrophila | OTC, OXA | NC | ND | |
| 2-333 | 10/98 | Sediment/outlet | NI | OTC, OXA | NC | ND | |
| 2-410 | 2/99 | Sediment/pond | A. bestiarum | OTC, S/T | A | dhfr1-ant(3′′)1a | |
| 3-30 | 10/97 | Sediment/outlet | A. hydrophila | OTC, S/T | NC | dhfr1-ant(3′′)1a | |
| 3-130 | 3/98 | Sediment/outlet | A. hydrophila | OTC, OXA, S/T | NC | ND | |
| 3-135 | 4/98 | Water/inlet | A. hydrophila | OTC | NC | ND | |
| 3-217 | 7/98 | Water/inlet | A. hydrophila | OTC | NC | ND | |
| 3-247 | 9/98 | Sediment/outlet | NI | OTC | NC | ND | |
| 3-372 | 2/99 | Water/pond | A. hydrophila | OTC, OXA, S/T | NC | dhfr2a-ant(3′′)1a | + |
| 4-90 | 11/97 | Rainbow trout | A. hydrophila | OTC, S/T | E | dhfr1-ant(3′′)1a | |
| 4-97 | 1/98 | Water/outlet | A. hydrophila | OTC, S/T | E | dhfr1-ant(3′′)1a-catB2 | |
| 4-206 | 6/98 | Sediment/pond | A. hydrophila | OTC, S/T | AE | dhfr1-ant(3′′)1a-catB2 | |
| 4-221 | 6/98 | Rainbow trout | A. veronii biovar sobria | OTC, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 4-229 | 7/98 | Rainbow trout | NI | OTC, OXA, S/T | A | dhfr1-ant(3′′)1a | + |
| 4-241 | 7/98 | Rainbow trout | A. veronii biovar sobria | OTC, S/T | NC | dhfr1-ant(3′′)1a-orf-catB2 | |
| 4-280 | 9/98 | Rainbow trout | A. bestiarum | OTC, OXA, S/T | NC | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 4-302 | 9/98 | Sediment/inlet | A. hydrophila | OTC | NC | No inserts | |
| 4-307 | 9/98 | Rainbow trout | A. veronii biovar veronii | OTC, OXA, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
| 4-348 | 9/98 | Rainbow trout | A. hydrophila | OTC, S/T | NC | dhfr1-ant(3′′)1a | |
| 4-353 | 9/98 | Sediment/inlet | A. hydrophila | OTC | NC | No inserts | |
| 4-354 | 9/98 | Sediment/inlet | A. bestiarum | OTC | E | No inserts | |
| 4-440 | 2/99 | Sediment/pond | A. hydrophila | OTC, S/T | A | dhfr1-ant(3′′)1a-orf-catB2 | + |
a
NI, no reliable identification of Aeromonas phenospecies.
b
NC, tetracycline resistance determinant not classified.
c
ND, not detected.
d
Tc + indicates the detection of transconjugants in filter mating assays, where Aeromonas donors transferred both their tetracycline (Tet) resistance determinant and class 1 integron on R-plasmids to E. coli recipients.