Isolation, Identification, and Drug Susceptibility Testing of the Pathogen Causing Perforation Disease in Giant Spiny Frog Tadpoles (Quasipaa spinosa)

A pathogenic bacterium strain, LBK2, was isolated from giant spiny frog (Quasipaa spinosa) tadpoles infected with perforation disease in this study. Pathogenic strain LBK2, a Gram-negative bacterium with a certain degree of infectivity, was demonstrated to cause anorexia, lethargy, epidermal necrosis, and abdominal perforation in tadpoles in artificial infection experiments. The identification results of 16S rDNA gene sequencing showed that pathogenic strain LBK2 was identified as Pseudomonas sp. Virulence gene identification displayed that strain LBK2 carried three virulence genes: aer, epr, and fla. Finally, the antibiotic susceptibility testing of 11 antibiotics suggested that strain LBK2 was highly sensitive to nine antibiotics, including chloramphenicol, enrofloxacin, and rifampicin, but was resistant to erythromycin, sulfamethoxazole/trimethoprim, and low-concentration trichloroisocyanuric acid. This study determined the pathogenicity of Pseudomonas sp. to giant spiny frog tadpoles based on histopathological analysis and virulence factor carriage, and the drug susceptibility testing further provided a scientific basis for the selection of drugs in the prevention and treatment of abdominal perforation disease in giant spiny frog tadpoles.