Bacterial diseases of cultured tiger frog (Rana tigerina)

Abstract

Diseased cultured tiger frogs (Rana tigerina), from 173 farms throughout Thailand, were submitted for diagnosis at Aquatic Animal Health Research Institute from 1994-1998. Bacterial species were isolated from sick frogs comprised of Aeromonas spp., Achromobacter sp., Citrobacter freundii, Flexibacter columnaris, Pseudomonas spp., Proteus spp., Serratia sp., Staphylococcus sp. and Streptococcus sp. Most bacterial isolates were characterized as aeromonads (51.68 %). Affected frogs showed the following clinical signs: haemorrhage of skin and/or internal organs, opaque eyes, ulcerative lesions on skin, and loss of appetite. Pathogenicity of the strains was tested by challenging healthy frogs. Histopathological study of experimentally infected frogs revealed inflammatory exudates, congestion and haemorrhages in the kidney, spleen, liver and muscle. The sensitivity of bacterial isolates to antimicrobial agents was examined using sulfamethoxazole/ trimethoprim, nitrofurantoin, chloramphenicol, oxytetracycline, streptomycin and erythromycin. Pseudomonad isolates showed the highest level of resistance, with more than 50 percent of isolates showing resistance to almost every antimicrobial tested.