Isolation, identification and antibiotic sensitivity of Elizabethkingia meningoseptica from Chinese sturgeon (Acipenser sinensis)

To define the potential pathogens from a dead F₂ Chinese sturgeon (Acipenser sinensis), which was reared in Taihu hatchery, a Chinese sturgeon breeding site located in Jingzhou City of Hubei Province, China, a bacterial strain EM was isolated from the liver, spleen and ascites of moribund F₂ Chinese sturgeon by traditional method of pathogen isolation. The strain EM was identified as Elizabethkingia meningoseptica by means of the 16S rDNA sequence, constructing phylogenetic tree and Biolog Microbial Identification System. The pathogenicity of the strain EM was confirmed by the infection experiment in healthy F₂ Dabry’s sturgeon (Acipenser dabryanus). Meanwhile, histopathological analysis was performed in the sick F₂ Chinese sturgeon, and the antibiotic susceptibility test of the strain EM was carried out to guide the clinical medication. The results found the hemosiderin deposition, ballooning degeneration and hemolysis severely in liver, spleen and kidney of the sick F₂ Chinese sturgeon. The strain EM was confirmed to be pathogenic to healthy Dabry’s sturgeon by infection experiment, and the same bacterium could be recovered from these infected Dabry’s sturgeon. The susceptibility test to antibiotics demonstrated that the strain EM from sick Chinese sturgeon was susceptible to minocycline, clindamycin, clarithromycin and midecamycin; medium susceptible to tetracycline, cefotaxime and cefoxitin, but resistant to other 28 kinds of antibiotics, which implied EM strain was resistant to multiple antibiotics. In short, the study reported for the first time that Chinese sturgeon could be infected by Elizabethkingia meningoseptica, which was also pathogenic to Dabry’s sturgeon. Preliminary study on biological characteristics, antibiotic susceptibility of Elizabethkingia meningoseptica, histopathological features of diseased F₂ Chinese sturgeon, may provide a theory basis for the diagnosis, prevention and treatment of this disease.