AUTHOR=Su Jie , Zhang Yingxue , Hu Tian , Ming Hongxia , Xie Yuyang , Jin Yuan , Shi Tingting , Fan Jingfeng 

TITLE=Prevalence, antibiotic and heavy metal resistance of Vibrio spp. isolated from the clam Meretrix meretrix at different ages in Geligang, Liaohe estuary in China

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1071371

DOI=10.3389/fmars.2022.1071371

ISSN=2296-7745

ABSTRACT=<p><italic>Vibrio</italic> as one of the main pathogens of shellfish diseases can cause serious human seafoodborne gastroenteritis and even death. In this study, we analyzed the bacterial communities from the clam, and compared the resistance phenotypes and genotypes of <italic>Vibrio</italic> spp. from <italic>Meretrix meretrix</italic> at different growth stages. High-throughput sequencing analysis revealed the predominance of <italic>Proteobacteria</italic> (50%) in the bacterial community and <italic>Vibrio</italic> was one of the dominant genera in the clam hepatopancreas in the summer. <italic>Vibrio</italic> abundance in <italic>Meretrix meretrix</italic> positively correlated with the water temperature (p&lt;0.05). A total of 73 <italic>Vibrio</italic> isolates from <italic>Meretrix meretrix</italic> were classified into 19 species and the dominant strains included <italic>V. mediterranei</italic> (19%) and <italic>V. harveyi</italic> (11%), <italic>V. algolyticus</italic> (10%), and <italic>V. parahaemolyticus</italic> (8%). The species and abundance of <italic>Vibrio</italic> spp. were the highest in the 3-year-old of <italic>Meretrix meretrix</italic> compared with clams of other ages in the summer. Among the 73 isolates, 68 <italic>Vibrio</italic> strains were resistant to other 15 antibiotics except for sulfamethoxazole-trimethoprim with 57 resistant phenotypes. The most prevalent resistance was toward clindamycin (76%), followed by amikacin (63%), ampicillin (62%), rifampicin (62%), vancomycin (57%), and amoxicillin (50%). The ARI values of <italic>Vibrio</italic> spp. in different ages ranged from 0.13 to 0.18, and ARI values of 3-year-old (ARI=0.18) clams are higher than that of other ages clam. Approximately 72% of the resistant isolates showed multidrug-resistant phenotypes with maximum resistance to 15 antibiotics. Tolerance to heavy metals including Cd, Zn, and Cu was detected in the majority of antibiotic resistant isolates. In addition to the co-resistance to the same class of antibiotics, resistance to cephalosporin (CFP, CEP, CZ) were significantly correlated with penicillins (AMP, AMC) (<italic>p</italic>&lt; 0.01), tetracycline (<italic>p</italic> &lt; 0.001), sulfanilamide (SXT) (<italic>p</italic>&lt; 0.01) and quinolone (CIP) (<italic>p</italic>&lt; 0.01). The heavy metal resistance genes <italic>copB</italic> and <italic>nccA</italic> were significantly correlated with the clindamycin resistance phenotype (<italic>p</italic>&lt;0.01). This study revealed that the habitat of <italic>Meretrix meretrix</italic> is in low exposure to antibiotics, and a link between heavy metal resistance genes and antibiotic resistance.</p>