Characterization of pRAS1-like plasmids from atypical North American psychrophilicAeromonas salmonicida

Abstract

Atypical psychrophilic Aeromonas salmonicida isolates were obtained from farmed and wild fish in Northeastern North America. These bacteria were isolated between 1992 and 2001 and carried tetracycline resistance (Tc(r)) plasmids of approximately 58 kb. The nine isolates had plasmids which could be divided into four groups based on the specific tetracycline resistance (tet) gene carried [tet(A) or tet(B)], incompatibility of the plasmid [IncU or other], whether the plasmid carried the IS6100 sequences, the sul1 gene, coding for sulfonamide resistance, the dfrA16 gene, coding for trimethoprim resistance, and/or carried a complete Tn1721, and their ability to transfer their Tc(r) plasmids to an Escherichia coli recipient at 15 degrees C. Five of the isolates, with genetically related Tc(r) plasmids, were able to transfer their plasmids to an E. coli recipient at frequencies ranging from 5.7x10(-4) to 2.8x10(-6) per recipient. The 1992 isolate carried a genetically distinct plasmid, which transferred at a slightly higher rate. The three remaining isolates carried one of two genetically different plasmids, which were unable to transfer to an E. coli recipient. Conjugal transfer at 15 degrees C is the lowest temperature that has been documented in bacteria.

Antimicrobial Resistance Patterns of Aeromonas spp. Isolated from Ornamental Fish

“…isolated, with no differences observed in these studied species. The resistance to tetracycline has been reported to be acquired and encoded by plasmids or transposons [26][27][28]. Ciprofloxacin and norfloxacin resistance was more prevalent among A. hydrophila isolates (43% and 34%, respectively) than the other species.…”

Genome Sequence of Aeromonas hydrophila ATCC 7966 T : Jack of All Trades

“…(13,75). Therefore, it is likely that other strains of A. hydrophila may possess such elements, unlike A. hydrophila ATCC 7966 T .…”

Unexpected Occurrence of Plasmid-Mediated Quinolone Resistance Determinants in EnvironmentalAeromonasspp.

“…E. coli TOP10 and azide-resistant E. coli J53 strains were recipient strains for transformation and conjugation experiments, respectively (20). Conjugation experiments were performed at 22°C and 37°C, as previously described (21). Transformants and transconjugants were selected on MH agar plates containing nalidixic acid (3 mg/L) only or containing azide (100 mg/L) plus nalidixic acid (6 mg/L), respectively.…”