Evaluation of Edwardsiella ictaluri virulence factors and antibiotic sensitivity pattern in experimental infection of climbing perch Anabas testudineus Available to Purchase

The Vietnamese climbing perch, Anabas testudineus, is a commercial and export-oriented aquaculture sector. However, intensive farming, mainly based on word-of-mouth recommendations and tremendous development, has resulted in an outbreak of harmful microbes. Besides that, the dietary effects of antibiotics on aquatic disease are circumstantial and have not been investigated under infection. The results revealed that E. ictaluri caused high virulence in climbing perch, with the behavioral and clinical signs usually followed by death. The virulence threshold of the bacterial concentration with an LD₅₀ of 1.58 × 10⁴ CFU/ml, the effect of erythromycin on the survival and infection rate of climbing perches A. testudineus following induced infection with antibiotic-resistant E. ictaluri was found in this study. The mortality rate in non-medicated artificially infected fish (93.33%) was considerably higher (p < 0.05) than that in medicated artificially infected fish (28.9%), and no mortality was recorded when injected with NaCl (0.85%). The levels of invasive erythromycin-resistant bacteria (ERB) in the kidney of artificially infected fish medicated for 5 days were significantly greater (p < 0.05, 3.5-4.8 times) than in non-medicated artificially infected fish. Overall, an antibiogram with an Edwardsiella ictaluri strain isolated from climbing perch confirmed that it was multi-antibiotic resistant with the beta-lactamase, lincosamide group, and exhibited intermediate resistance to erythromycin. According to the facts, climbing perch collected in Ho Chi Minh City (HCMC) was found to be infested not only with extremely pathogenic bacteria but also with multi-antibiotic resistant strains, posing a threat to human health. As a result, further research on antibiograms and/or innovative techniques for managing aquatic diseases should be conducted employing mixed infections and pathogen interactions to benefit the optimum treatment.