ABSTRACT
Structure analysis was performed on the antibiotic-resistance-gene region of conjugative plasmids of four fish farm bacteria.The kanamycin resistance gene, IS26, and tetracycline resistance gene (tetA(D)) were flanked by two IS26s in opposite orientation in Citrobacter sp. TA3 and TA6, and Alteromonas sp. TA55 from fish farm A. IS26-Inner was disrupted with ISRSB101. The chloramphenicol resistance gene, IS26 and tetA (D) were flanked by two IS26s in direct orientation in Salmonella sp. TC67 from farm C. Structures of tetA (D) and IS26 were identical among the four bacteria, but there was no insertion within the IS26-Inner of Salmonella sp. TC67. Horizontal gene transfer between the strains of two different genera in fish farm A was suggested by the structure homologies of mobile genetic elements and antibiotic resistance genes.
Subject(s)
Bacteria/genetics , DNA Transposable Elements , Fishes/microbiology , Genes, Bacterial , Animals , Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Bacteria/isolation & purification , Drug Resistance, Bacterial , Gene Order , Microbial Sensitivity Tests , Tetracycline/pharmacologyABSTRACT
Three variants of the composite transposon Tn10 were extracted from transferable plasmids of fish farm bacteria. These variants were identical in insertions with IS10, but differed in another class I transposon insertion and a region of homologous recombination downstream of tetB.
Subject(s)
Bacteria/genetics , Bacterial Proteins/genetics , DNA Transposable Elements , Fishes/microbiology , Fresh Water/microbiology , Animals , Bacteria/classification , Bacteria/isolation & purification , Bacteria/metabolism , Bacterial Proteins/metabolism , Base Sequence , Molecular Sequence DataABSTRACT
Tetracycline-resistant (Tet(r)) bacteria were isolated from fishes collected at three different fish farms in the southern part of Japan in August and September 2000. Of the 66 Tet(r) gram-negative strains, 29 were identified as carrying tetB only. Four carried tetY, and another four carried tetD. Three strains carried tetC, two strains carried tetB and tetY, and one strain carried tetC and tetG. Sequence analyses indicated the identity in Tet(r) genes between the fish farm bacteria and clinical bacteria: 99.3 to 99.9% for tetB, 98.2 to 100% for tetC, 99.7 to 100% for tetD, 92.0 to 96.2% for tetG, and 97.1 to 100% for tetY. Eleven of the Tet(r) strains transferred Tet(r) genes by conjugation to Escherichia coli HB-101. All transconjugants were resistant to tetracycline, oxycycline, doxycycline, and minocycline. The donors included strains of Photobacterium, Vibrio, Pseudomonas, Alteromonas, Citrobacter, and Salmonella spp., and they transferred tetB, tetY, or tetD to the recipients. Because NaCl enhanced their growth, these Tet(r) strains, except for the Pseudomonas, Citrobacter, and Salmonella strains, were recognized as marine bacteria. Our results suggest that tet genes from fish farm bacteria have the same origins as those from clinical strains.
