The first evidence of blaCTX-M-55, QnrVC5, and novel insight into the genome of MDR Vibrio vulnificus isolated from Asian sea bass (Lates calcarifer) identified by resistome analysis

Vibrio vulnificus is a bacterium that causes vibriosis and exhibits resistance to many antimicrobials. To comprehensively understand V. vulnificus resistance, four MDRs isolates were selected for resistome analysis. Based on the Average Nucleotide Identity (ANI) and DNA-DNA hybridization (DDH), all isolates showed a high identity score to the V. vulnificus ATCC 33147. Likewise, multilocus sequence typing (MLST) showed that CUVETSS48 isolate was founded closer to two STs (409 and 570), while the others (CUVETCC1, CUVETCC2, and CUVETSS2) were founded closer to a single ST (209, 426, and 372, respectively). MIC determination showed that all isolates were resistant to Amoxicillin and Colistin sulfate, but only two isolates (CUVETCC1 and CUVETSS48) were resistant to all tested antimicrobials. Referring to resistome analysis, multiple antibiotic resistance genes (ARGs) were found, such as QnrVC1, QnrVC7, tetR, tetB, and blaCTX-M-55 (CUVETCC1); tet(59), sul2, and QnrVC5 (CUVETSS48). Moreover, a mutation was founded within the QRDR region of gyrA; S83I (CUVETCC1, CUVETCC2, and CUVETSS48), gyrB; K87N (CUVETCC2, SS2, and SS48), and parC; S80Y (CUVETCC1 and CUVETCC2). In conclusion, this study showed the first evidence for the presence of blaCTX-M-55, QnrVC5 anti- microbial resistance genes, as well as mutations in gyrA, gyrB, and parC genes (at positions 83, 87, and 80) among V. vulnificus isolates. The presence of multiple ARGs may contribute to the MDR phenotype of V. vulnificus.