Occurrence and distribution of tetracycline resistance determinants and their pollution profile in selected aquaculture environments in Sri Lanka

Abstract

Tetracycline (TET) has been extensively used in aquaculture for chemotherapy against various fish diseases. The contamination levels in 16 aquaculture farms in Sri Lanka were analysed using high performance liquid chromatography (HPLC). The presence of antibiotic-resistant bacteria was identified using the 16SrRNA gene sequencing and the corresponding antibiotic resistant genes (ARGs) were screened at each location using the PCR method. The concentration of TET in the aquaculture farm samples ranged between 0.001± 0.001 - 0.112± 0.017 ppm. Bacillus and Staphylococcus were recorded as the most dominant resistant bacterial genera against TET. Acinetobacter sp., Achromabacter sp., Staphylococcus sp., Micrococcus sp. were also identified as resistant bacteria. In the present study, tet (M) and tet (A) were the abundant resistance genes (11/16 isolates), followed by tet (S) (5/16) and tet (B) (4/16). It was found that tet (M) is one of the most widely distributed tetracycline resistance determinants in the aquaculture environment in Sri Lanka.