Isolation,identification and susceptibility of Aeromonas veronii from diseased northern sheatfish Silurus soldatovi
LU Meng-ying1, HU Xiu-cai1, Lü Ai-jun1, SUN Jing-feng1, CHEN Cheng-xun1, WANG Xiao-mei1, YEONG Yiksung1,SONG Ya-jiao2
1.Tianjin Key Laboraory of Aqua-Ecology and Aquaculture, College of Fisheries, Tianjin Agricultural University, Tianjin 300384, China; 2.College of Fisheries, Henan Normal University, Xinxiang 453007, China
Abstract: A bacterial strain, called as strain SG-1, isolated from liver of diseased northern sheatfish Silurussoldatovi was shaped-rod and gram-negative bacterium by Gram-staining and identified as Aeromonasveronii by morphological, physiological and biochemical characteristics as well as the 16S rDNA gene sequencing and phylogenetic tree analysis. The isolated strain was shown to be characterized by glucose gas production, positive oxidase, nitrate reduction, negative ornithine decarboxylase and hydrogen sulfide. Further fragment size of 16S rDNA sequence amplified by PCR was 1409 bp, and had 99.86% similarity with Aeromonasveronii ATCC35624 type strain. Phylogenetic tree analysis revealed that the isolate was clustered with Aeromonasveronii. The northern sheatfish and zebrafish Daniorerio chalenged with Aeromonasveronii had mortality rate of 100%, showing surface bleeding, anal swelling, and ascites. Susceptibility test showed that the isolate was sensitive to cefixime, cefoperazone, cefotaxime, norfloxacin, levofloxacin, enrofloxacin, and florfenicol, but resistant to amoxicillin, ampicillin, sulfisoxazole, methoxy pyrimidine, and cotrimoxazole.
2017, Vol. 32 
