Distribution of Vibrionaceae in farmed Asian sea bass, Lates calcarifer in Thailand and their high prevalence of antimicrobial resistance

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 desorp- tion/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. According to a laboratory challenge experiment, among the six isolates, only V. har- veyi 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 28 of 29 resistance profiles were multidrug resistances (MDR), with V. vulnificus having the highest MAR value (0.66). The findings of this study advise that a surveillance program, as well as preventive and control measures, be developed for Vibrionaceae to reduce production loss, pathogen proliferation, and antibiotic abuse, whereas AMR data indicate substantial health problems for aquatic animals and humans.