Objective: The aim of this study was molecular characterization of the antibiotic resistance in 43 coliforms isolated from the east coastal zone of Black Sea, Turkey.

Materials and Methods: All strains were screened for resistance to certain antibiotics by disk diffusion method. TEM-type β-lactamase gene in ampicillin-resistant strains, class 1 and class 2 integron gene cassettes and tetracycline resistance determinants in tetracycline-resistant strains were investigated by polymerase chain reaction. Plasmid transformation experiments were performed by heat shock method.

Results: We found that 17 (39.5%) strains were resistant to one or more antibiotics. One ampicillin-resistant Escherichia coli strain harbored a TEM-1 type β-lactamase gene. tet(B) gene was common among tetracyclineresistant strains. One E. coli strain carried a 2.0-kb class 1 integron, and one E. coli carried a 2.2-kb class 2 integron. DNA sequencing results demonstrated that class 1 and class 2 integrons contained blaOXA-30-aadA1 and dfrA1-sat2-aadA gene cassette arrays, respectively. Resistance to ampicillin, tetracycline or streptomycin was transferable traits.

Conclusion: We are of the opinion that there are antibiotic resistance determinants in coliforms of human origin in marine environment, carrying a risk for public and environmental health. To our knowledge, this is the first report for class 1 and class 2 integrons in coliform bacteria isolated from sea water in Turkey.