Full Length Research Paper

Intergenic and intragenic conjugal transfer of multiple antibiotic resistance determinants among bacteria in the aquatic environment of Bangladesh

Hasan M. Zahid¹* Zinat Mahal² and Mamun R. Chowdhury²

¹Tissue Banking and Biomaterial Research Unit, Bangladesh Atomic Energy Commission, Atomic Energy Research Establishment, G.P.O. Box No.-3787, Dhaka-1000, Bangladesh.

²Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka-1000, Bangladesh.

*Corresponding author. E-mail: zahid_bmb@yahoo.com. Tel: +88 02 7701679. Fax: +88 02 8613051.

Accepted 30 September, 2008

Conjugation process was conducted to determine the means of transferring multiple loci of antibiotic resistant gene among bacteria in the surface water of Bangladesh. Our observation demonstrated that tetracycline resistant gene can be spread between bacteria in the aquatic environment. In this study, it was surprisingly observed that tetracycline resistant gene was transferable horizontally by conjugation process from Vibrio cholerae to Esherichia coli (intergenic) and E. coli to E. coli (intragenic) in combination with sulphamethoxazole-trimethoprim (SXT), streptomycin and erythromycin as a self transposable tetracycline element. In intergenic transfer, conjugation frequency was more than intragenic transfer. Frequencies of transfer generally ranged from 10^-5 to 10^-3 transconjugants per input donor and recipient cell. The results of these experiments suggested that the mobility of the antibiotic resistance determinants may further contribute to the development and spread of antibiotic resistance among pathogenic bacteria, particularly since antibiotics are indiscriminately used in Bangladesh.

Key words: Conjugation, gene transfer, aquatic environment.