Identification of Pathogenic Bacteria from Diseased Thai Pangas Pangasius hypophthalmus with Their Sensitivity to Antibiotics

Thai Pangas (Pangasiaus hypophthalmus) has been emerging as an economically very important species due their faster growth, year round production and high productivity in South-East Asian aquaculture. It has good market value as a food fish due to its good taste and deliciousness with high protein, minerals and fat content. It is also popular as a game fish.

Aims: The present study was conducted to identify bacterial pathogens in diseased P. hypophthalmus and evaluate their sensitivity to antibiotics.

Methodology: To identify the causativeagent of diseased fish pure culture of bacteria using slant and streak plate techniques and different biochemical tests such as Gram’s Staining, Motility Test, Sugar Fermentation Test, MR-VP test, Indole Test etc. were performed. To assess the sensitivity of the isolated bacteria to antibiotics five antibiotics disks i.e. Ciprofloxacin (5μg), Azithromycin (15μg), Ampicillin/Sulbactam (20μg), Tetracycline (30μg) and Erythromycin (15μg) were used.

Results: Three pathogenic bacteria i.e. Aeromonas hydrophila, Edwardsiella ictaluri and Pseudomonas sp. were identified in the studied diseased fish. Only Pseudomonas sp. were identified from Fresh fish. E. ictaluri was found only in diseased pangas which was the causative agent for thedisease, Bacillary Necrosis. The results of the antibiotic sensitivity test showed multi-resistances of the identified bacteria to the tested antibiotics. The identified bacteria were 100% sensitive to Ciprofloxacin (5μg), intermediate to Azithromycin (15μg) and Tetracycline (30μg), but resistant to Erythromycin (15μg) and Ampicilin/Sulbactam (20μg).

Conclusion: Ciprofloxacin (5µg) could be used to control bacillary necrosis disease in Thai pangas. The results of this study will be helpful to the fish farmers for the management of bacterial diseases in fish.