Genetic Relationship, Virulence Factors, Drug Resistance Profile and Biofilm Formation Ability of Vibrio parahaemolyticus Isolated From Mussel

Occurrence of Virulence and Extended-Spectrum β-Lactamase Determinants in Vibrio spp. Isolated from Marketed Hard-Shelled Mussel (Mytilus coruscus)

This study investigated the occurrence of virulence and antimicrobial resistance properties in Vibrio spp. isolated from hard-shelled mussel (Mytilus coruscus) marketed in Korea. A total of 32 Vibrio spp. isolates including Vibrio diabolicus (n = 16), Vibrio alginolyticus (n = 13), Vibrio parahaemolyticus (n = 2), and Vibrio harveyi (n = 1) were identified by gyrB gene sequencing. Every isolate grouped with their respective reference sequence excluding V. diabolicus and V. alginolyticus that were intermixed in a neighbor-joining phylogenetic tree. Every Vibrio spp. showed DNase and gelatinase activities. Phospholipase, slime, caseinase, lipase, β-hemolysis, and α-hemolysis were positive in 31 (96.8%), 31 (96.8%), 29 (93.5%), 28 (87.5%), 17 (53.1%), and 9 (28.1%) isolates, respectively. The PCR amplification of virulence genes displayed that V. alginolyticus-specific (toxR, tlh, VAC, and VPI) genes were detected in 23 (71.9%), 18 (56.3%), 21 (65.6%), and 26 (81.3%) isolates, respectively. V. parahaemolyticus-specific (toxR and tlh) genes were harbored by 2 (6.3%) and 2 (6.3%) isolates, respectively. The other virulence genes including ctxAB and hupO genes were observed in 23 (71.9%) and 16 (50.0%) isolates, respectively. The antimicrobial resistance was prevalent for amoxicillin (100.0%), ampicillin (100.0%), and streptomycin (37.5%) in disk diffusion test. Multiple antimicrobial resistance index ranged from 0.09 to 0.22. The extended-spectrum β-lactamase (ESBL) genes, blaCTX, blaTEM, blaSHV, and blaOXA were detected in 28 (87.5%), 13 (40.6%), 7 (21.8%), and 1 (3.1%) isolates, respectively. Non-ESBLs such as streptomycin resistance (strA.B), kanamycin resistance (aphA-IAB), and tetracycline resistance (tetE) genes were found in 5 (15.6%), 3 (9.4%), and 1 (3.1%) isolates. Class 1 integron-related Integrase 1 (intI1) gene was found in 8 (25.0%) isolates. Our results reveal that the consumption of raw mussels may cause a potential public health risks owing to the virulent and antimicrobial-resistant Vibrio spp.