| Summary: | Seawater has been proposed as a reservoir for antibiotic-resistant bacteria and antibiotic resistance genes, thus representing a risk to public health. In this study, we evaluated the presence of antibiotic resistance determinants (bacteria and genes) in 77 seawater samples collected at different points along the coast of the Gulf of Valencia (Spain). Specifically, indicators of fecal contamination bacteria, <i>Escherichia coli</i> and <i>Enterococcus</i> sp., were isolated, and their antibiotic resistance profiles were analyzed through the use of the Sensititre<sup>®</sup> system, followed by the detection of the main antibiotic resistance genes (<i>bla</i>TEM, <i>qnr</i>S, <i>tet</i>W, <i>sul</i>I, and <i>erm</i>B). The highest frequencies of resistance in the <i>E. coli</i> isolates were detected for ampicillin (35.1%) and ciprofloxacin (17.5%), followed by sulfamethoxazole and trimethoprim (15.7%), while 23% of enterococci isolates showed resistance to a single antibiotic, 20% against tetracycline and 3% against daptomycin. Through PCR analysis, 93% of the <i>E. coli</i> strains showed the <i>bla</i>TEM and <i>sul</i>I resistance genes. Among the enterococci, the presence of the <i>bla</i>TEM gene was detected in 40% of the isolates, while the rest of the genes were present at very low rates. Among the water samples, 57% were positive for at least one of the tested genes, italic format with <i>bla</i>TEM being the most commonly found gene (47%), followed by the <i>qnr</i>S (33%) and <i>sul</i>I (23%) genes. These results show that seawater, in addition to being subjected to a high rate of fecal contamination, can contribute to the spread of antibiotic resistance.
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