Diagnostics and prevention of aeromonosis Cyprinus sagrio

Abstract

Relevance. Aeromonosis (carp rubella, hemorrhagic septicemia, infectious abdominal dropsy, Lublin disease) — an infectious disease of fish. Carp, common carp and their hybrids from underyearlings to broodstock are susceptible to the disease. The epizootic reaches its greatest distribution in the spring-summer period, by autumn it fades and the disease takes on a chronic course.Methods. The object of research was the fish Cyprinus carpio. In the experiments, we used the reference strain Aeromonas hydrophila ATCC 7966 of the Global Center for Bioresources, as well as isolates isolated during outbreaks of carp aeromonosis in fish farms in the Moscow region. The diagnosis for the presence of aeromonosis was established on the basis of epizootological, clinical and pathological data and the results of bacteriological studies. The study of biofilms of microorganisms was carried out during cultivation in liquid nutrient media, the CFU of microorganisms was counted and sown on the surface of solid media.Results.The total number of microorganisms (CFU, lg/g) of intestinal microbiocenoses— 54,21 ±0,05 – 66,09 ±0,12. Cultures of microorganisms A. hydrophyla, A. sobria, A. caviae were isolated from blood, heart, spleen, gills, intestine, liver and kidneys of fish. During cultivation at 37 °C for 6–72 h, the adhesion of vegetative forms of bacteria with a typical shape and size of the species and the formation of a bacterial monolayer — a diffuse layer of bacterial cells — was revealed. Viable and non-viable microorganisms were differentiated by fluorescence microscopy. On meat-peptone agar with 5,0% of defibrinated blood, as a rule, the growth of b-hemolytic colonies was observed, less often a-hemolytic colonies. When determining the enzyme DNase, a light zone was found along the inoculation line on the DNA BA medium. Growth of b-hemolytic cultures was observed on meat-peptone agar with 5,0% of defibrinated blood. When determining the DNase enzyme on the surface of the dense nutrient medium “DNA BA”, a light transparent zone was revealed around the colonies of microorganisms. Prevention of aeromonosis is based on systematic monitoring of the etiological structure of pathogens of aeromonosis; feeding in feeding and summer mother ponds begins in the spring when the water temperature rises to 14 °C.