Pathogenicity and drug susceptibility of type ST251 high pathogenicity Aeromonas hydrophila strain straind from black carp (Mylopharyngodon piceus)
WANG Lingling，HOU Tianmu，LI Huaming，XIANG Wei，YUAN Hanwen，LEI Liancheng，ZHANG Fuxian*
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1.College of Animal Science，Yangtze University，Jingzhou 434023，China；2.Engineering Research Center of Ecology and Agricultural Use of Wetland，Ministry of Education，Jingzhou 434023，China；3.Key Laboratory of Waterlogging Disasters and Wetland Agriculture of Hubei Province，Jingzhou 434023，China；4.College of Veterinary Medicine，Jilin University，Changchun 130062，China
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Published
2023-11-06
Issue Date
2023-11-06
Abstract
In order to determine the pathogen and pathogenicity of black carp(Mylopharyngodonpiceus)(body weight from 1.0 kg to 1.5 kg) with hemorrhagic disease caused in a farm in Jingzhou, Hubei Province, a dominant strain QAB5 was isolated from diseased black carp using the traditional pathogen isolation method, and its morphological characteristics, physiological and biochemical properties were investigated by 16S rRNA gene sequence, multiple sequence locus typing, extracellular enzyme activity analysis, virulence gene detection, artificial infection test, biofilm forming ability determination and drug sensitivity test. The results showed that strain QAB5 was Aeromonashydrophila with strong pathogenicity, and had the MLST sequence type of ST251, containing hemolytic activity, protease and lipase activity, carrying six virulence genes such as aer+hly+ahp+ast+alt+act+. Artificially infected healthy black carp showed symptoms similar to naturally diseased black carp such as unresponsiveness, abdominal bleeding, anal redness and swelling, and intestinal bleeding, with median lethal dose (LD50) of 4.4×106 CFU/mL, a highly pathogenic and virulent strain. The isolated strain QAB5 was found to be sensitive to 13 antibacterial drugs including kanamycin and chloramphenicol, and moderately sensitive to penicillin; and sensitive to Chinese herbal medicines whole scorpion, Fructus Mume and clove had obvious inhibitory effect on the isolated strain QAB5 invitro. The results showed that the isolated strain QAB5 was a virulent strain of ST251 Aeromonashydrophila, which was the pathogen causing black carp hemorrhagic disease.Highly sensitive antibacterial drugs such as ciprofloxacin and tetracycline, combined with biofilm scavengers, are recommended for precise treatment in small doses.
WANG Lingling, HOU Tianmu, LI Huaming, XIANG Wei, YUAN Hanwen, LEI Liancheng, ZHANG Fuxian.
Pathogenicity and drug susceptibility of type ST251 high pathogenicity Aeromonas hydrophila strain straind from black carp (Mylopharyngodon piceus)[J]. Journal of Dalian Fisheries University, 2023, 38(4): 573-583 https://doi.org/10.16535/j.cnki.dlhyxb.2022-290
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