Survey of Antibiotic Resistant Bacteria in Ulleungdo, Korea

BACKGROUND: Although antibiotics have contributed to treatment of bacterial infection, the antibiotic abuse can lead to antibiotic resistant bacteria. Impact of human ac-tivities on distribution of antibiotic resistance has been in-tensively issued and occurrence of antibiotic resistant bacteria in contaminated environments would not be a surprise. Nonetheless, anthropogenic contamination with the dissemination of antibiotic resistance along uncon-taminated environments has been less considered. The aim of this study is to investigate antibiotic resistant bacteria across Ulleungdo, known as antibiotic resistance free and anthropogenic pollution free environment in Rep. of Korea. METHODS AND RESULTS: Antibiotic resistant bacteria in coastal seawater of Ulleungdo were investigated in July 2021. Antibiotic susceptibility test using the disk diffusion method was applied with six drugs according to the Clinical and Laboratory Standards Institute (CLSI) guide-line. Total 43 bacterial isolates were tested and 20 isolates among of them showed multidrug resistance. Particularly, the number and ratio of resistant bacteria were relatively high in a densely populated area of Ulleungdo. The bacterial communities were investigated using 16S rRNA gene metabarcoding approach in the coastal seawater and soils of Ulleungdo. In the bacterial communities, Firmicutes were selectively distributed only in seawater, suggesting the possibility of anthropogenic contamination in coastal seawater of Ulleungdo. CONCLUSION(S): We found antibiotic resistant bacteria in a populated area of Ulleungdo. The occurrence of antibiotic resistant bacteria in Ulleungdo seems to result from the recent anthropogenic impact. Consistent monitoring of antibiotic resistant bacteria in the uncontami-nated environment needs to considered for future risk assessment of antibiotics.