Identification of Acinetobacter schindleri isolated from Chinese giant salamanders (Andrias davidianus)

Abstract

At a particular aquaculture facility in Zhangjiajie in China, the Chinese giant salamander (Andrias davidianus) exhibited analogous clinical manifestations, culminating in sequential mortalities. This study used rigorous aseptic sampling methods to isolate bacteria from the affected liver of salamanders to determine the causative agent behind the decline in amphibians. A bacterial pathogen was isolated from diseased A. davidianus, and the strain was named DN-3. This isolate was subjected to bacterial identification, antibiotic susceptibility assays, reinfection experiments, and biochemical profiling. The isolated bacterial strain was definitively identified as Acinetobacter schindleri using 16S rRNA sequence analysis and biochemical identification. Antibiotic susceptibility testing revealed that this isolate was susceptible to neomycin, macrolides, doxycycline, piperacillin, nitrofurantoin, and carbenicillin. Subsequent reinfection assays, in which varying concentrations of the bacterial inoculum were administered to healthy salamanders, confirmed that the pathogen elicited varying degrees of morbidity or mortality within an eight-day observation period. The median lethal dose (LD50) of A. schindleri DN-3 for A. davidianus was calculated to be 6.25×104 CFU/mL. This result supports the significant pathogenicity of the strain for A. davidianus. The findings of this study provide empirical insights into the clinical management and epidemiological control of diseases affecting A. davidianus.