Genetic characterizations, virulence, antimicrobial resistances and resistome analysis of vibrio spp. Isolated from farmed Asian sea bass (Lates Calcarifer) in Thailand

Abstract

This study describes the etiological agent of Vibriosis along with its distribution and antimicrobial resistance profiles among farmed Asian sea bass (Lates calcarifer) in Thailand. The study isolated 283 Vibrionaceae from 15 Asian sea bass farms located around the provinces of the Andaman Sea and Gulf of Thailand coasts to uncover the distribution and antimicrobial resistance profiles. Bacterial identification based on a combination of the biochemical characteristics, Matrix-assisted laser desorption/ ionization-time of flight (MALDI-TOF) mass spectrometry (MS) analysis, and the species-specific PCR demonstrated the predominant Vibrionaceae were Vibrio harveyi (n = 56), Photobacterium damselae (n = 35), and V. vulnificus (n = 31), respectively. Characterization based on MALDI-TOF MS and 16S rRNA showed that Harveyi clade followed by V. vulnificus and V. navarrensis formed a big clade in this study. According to a laboratory challenge experiment, among the six isolates, only V. harveyi was found to cause clinical signs of muscle necrosis and scale loss in Asian sea bass. Antibiotics resistance test results exhibited high resistance to antibiotics such as metronidazole (100%), streptomycin (97%), clindamycin (96%), colistin sulphate (70%), and amoxicillin (59%). Remarkably, 100% of Vibrionaceae isolates are susceptible to florfenicol. The 20 of 29 resistance profiles were multidrug resistance (MDR), with V. vulnificus having the highest MAR value (0.66). Resistome analysis also found that MDR V. vulnificus carried blaCTX-M-55, qnrVC5, and mutation in gyrB and parC (positions 87 and 80), which is not reported previously in this species. The findings of this study advise that a surveillance program, as well as preventive and control measures, be developed for Vibrio spp. to reduce production loss, pathogen proliferation, and antibiotic abuse, whereas AMR data indicate substantial health problems for aquatic animals and humans.