Oceanological and Hydrobiological Studies

We investigated the frequency of antibiotic resistance of Enterobacteriaceae and the presence of vancomycinresistance genes in samples taken from the Sea of Marmara, and the Istanbul and Canakkale Straits, Turkey. Di erent colony-forming bacteria were isolated and identi ed with the VITEK 2 Compact 30 system. e antibiotic resistance of the isolates was determined by the disc di usion method. e isolates were tested against amoxicillin, ampicillin, aztreonam, ce azidime, cefotaxime, cefuroxime, o oxacin, vancomycin, tetracycline, kanamycin and gentamycin. e presence of vancomycin-resistance genes (vanA and vanB) was also investigated. e level of Enterobacteriaceae species was higher in the Sea of Marmara than in the Istanbul Strait and the Canakkale Strait. Isolates showing resistance to the greatest number of antibiotics were identi ed from E. coli isolates. e resistance of the selected bacterial isolates were as follows: kanamycin (82%), vancomycin (78%) and ampicillin (60%). Some intermediately vancomycin-resistant Enterobacteriaceae isolates had the vanA gene. is study provides evidence of widespread bacterial resistance to clinically relevant antibiotics in marine environments. It also contributes to the knowledge on the distribution of antibiotic resistance among Enterobacteriaceae and indicates the importance of control measures in domestic water treatment.