Isolation, Identification and Genomic Analysis of Plesiomonas shigelloides Isolated from Diseased Percocypris pingi (Tchang, 1930)

Recently, the outbreak of a serious infectious disease of unknown etiology was noted in Percocypris pingi (Tchang, 1930) farms in Yunnan province. Due to currently limited information, we aimed to identify the pathogen isolates, determine the susceptibility of the isolates, evaluate the pathogenicity and analyze the genome of the representative strain. Ten strains of Gram-negative rods were isolated from diseased P. pingi and the isolates were identified as Plesiomonas shigelloides based on biochemical characteristics, 16S rRNA gene sequencing and species-specific PCR detection. The results of susceptibility analysis showed that two selected strains LS1 and LL2 were resistant to ampicillin, penicillin G, trimethoprim/sulfamethoxazole, tetracycline, enrofloxacin, nalidixic acid and enoxacin. A virulence assay indicated that the pathogen was virulent to zebrafish. Genomic analysis revealed that the LS1 isolate was closely related to strain GN7, which was isolated from animal farms. To the best of our knowledge, this is the first report of P. shigelloides as a pathogen of P. pingi. This study will provide a rational framework for exploration of epidemiological analysis of P. shigelloides in fish diseases and would further benefit conservation of the species.