Diversity and antibiotic resistance of bacteria from bathing beaches: based on the cultivation method

Abstract:

[Objective] The increasing antibiotic resistant bacteria (ARB) caused by the horizontal transfer of antibiotic resistance genes (ARGs) have aroused increasing concern, and it is particularly important to monitor the ARB in the environment. [Methods] We collected seawater and sand samples from three different bathing beaches in Zhanjiang. The plate coating method and agar diffusion method were employed to study the bacterial counts, diversity, and susceptibility to antibiotics. [Results] The seawater samples had higher content of inorganic nitrogen than the normal value and the bacterial counts increased with the increase in the visitor flow. The bacteria counts in the sand samples were higher than those in the seawater samples. The bacteria from the bathing beaches belonged into 18 genera, 12 families of 3 phyla. Proteobacteria (49.64%) was dominant in the seawater samples, while Firmicutes (54.74%) was dominant in the sand samples. The bacteria showed stronger resistance to beta-lactams, with the resistance rates of 23.25%, 20.53%, and 17.42% to penicillin, vancomycin, and ceftriaxone, respectively. The resistant bacteria were mainly Bacillus, Vibrio, Pseudomonas, Streptomyces, and Enterobacter. The multidrug-resistant bacterial strains from seawater were significantly more than those from sand, and increased with the increase in the visitor flow. [Conclusion] There are diverse drug-resistant bacteria from bathing beaches, and continuous surveillance is required to assess its potential impact on public health.