AUTHOR=Huang Ziwei , Anokyewaa Melody Abena , Wang Junlin , Jian Jichang , Lu Yishan 

TITLE=Pathogenicity and antibiotic resistance analysis of Vibrio species found in coastal water at mainly beach of Shenzhen, China

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.980593

DOI=10.3389/fmars.2022.980593

ISSN=2296-7745

ABSTRACT=<p>Offshore industries and resources are the links between humans and the marine ecosystem. Several risk factors are associated with beach activities. The risk of <italic>Vibrio</italic> infection at bathing beaches is often overlooked as there are virtually no regulations regarding them. In this study, we investigated the current prevalence of pathogenic <italic>Vibrio</italic> spp. on the main beaches of Shenzhen. The risk indicator levels of pathogenic <italic>Vibrio</italic> species obtained were analyzed using 17 virulence genes mainly associated with <italic>Vibrio</italic> species and are responsible for several ailments and infections. A total of 60 <italic>Vibrio</italic> strains were isolated and identified by morphological observation, evolutionary tree alignment, and biochemical testing. There was a high abundance of <italic>Vibrio</italic> in the seawater. Also, a positive correlation was observed between the presence of virulence genes and the exhibition of high pathogenicity after artificially infecting fish with some of the virulent <italic>Vibrio</italic> species. In the infection experiment, it was observed that all the zebrafish infected with <italic><italic>MEDF7</italic></italic> (<italic>Vibrio alginolyticus</italic>) and <italic>JSW-YELLOW</italic> (<italic>Vibrio harveyi</italic>) died a day after injection, with varying degrees of abdominal enlargement and skin ulceration. The mortality rates for strains with medium risk and low risk were 65% and 45%, respectively. Lethal dose 50 (LD<sub>50</sub>) values were 5.67 ×10<sup>4</sup> CFU/fish, 3.72 ×10<sup>5</sup> CFU/fish, and 4.31 ×10<sup>5</sup> CFU/fish for the high-risk, medium-risk, and low-risk strains of zebrafish, respectively. The results of the antibiotic sensitivity test showed that all the six experimental strains, except <italic>JSW-YELLOW</italic>, were resistant to doxycycline and neopenicillin. In summary, our study first identified and evaluated the pathogenicity of <italic>Vibrio</italic> in the Shenzhen beach baths, serving as a scientific benchmark for <italic>Vibrio</italic> risk prevention and control as well as guidance for <italic>Vibrio</italic> diagnosis through virulence factor detection and risk classification.</p>