The Aeromonas Hydrophila Sepsis Pathogen Of Northern Pike(Esox Lucius) Isolation, Identification And Pathogenic Research

Northern Pike(Esox lucius) is one of the major indigenous economic fish in Xinjiang, itbelongs to the ferocious carnivorous cold-water fishes. It early began of artificial breeding inXinjiang, but has become a scale. With the high density of intensive aquaculture, fish baitsource and other reasons, led to disease problem immediately. The outbreak of bacterialsepsis is one of the main diseases of Northern Pike farming, causing huge economic losses inlocal aquaculture. Using drug to prevent and control the bacterial sepsis is a major means oflocal occurrence, but it may induce pathogen developing drug resistance, causing the organ offish body such as liver and kidney function is damaged, and creating the food safety issuessuch as drug residues. In this paper, The main research is isolating and distinguishingpathogen from Northern Pike that developed the disease of Aeromonas hydrophila sepsispathogen in Xinjiang, analyzing the pathological histology of diseased organs, as well asresearching the sensitivity of multiple antimicrobial drugs for the separation strains. In theanalysis of the characteristics of pathogenic bacteria in the disease process, the accumulationof basic material lay a foundation for improving the control effect.This research isolated13strains from natural conditions with suspected bacterial sepsis ofPike, completing morphology observation, physiological and biochemical characteristics ofidentification and by the molecular biology identifying the virulence factors of strains, somestrains of artificial infection test proved its pathogenicity. The determination results show that:PK001to PK009et al.13isolates of physiological and biochemical characteristicsmaintained basically consistent with Aeromonas hydrophila. By molecular biology methodsdetermination of16SrRNA and virulence factors identified13strains as Aeromonashydrophila, is the main pathogenic bacteria can infect fish bacterial sepsis.The resultsfollowing:The artificial infection experiments of Pike with PK001, PK006isolates contained threevirulence genes, found that the symptoms similar to natural cases, mortality rate of80%or more; and the same bacteria isolates from kidney, liver tissue of dying Pike identified in linewith the original pathogen. With carp as isolates of virulence test (ahpA, hlyA and aerA gene)object, respectively by three, two, one and none virulence genes of strain PK001, PK002,PK005, PK009infection carp, finding that the mortality have many difference between.Artificial infection of the results found that strains containing toxic gene types affect its lethalforce, strain virulence genes contained less the virulence of the weaker.By analyzing the pathology changes of the disease from Pike concluded that: infectionand pathogenesis of pike have obviously ulcer, blood loss and other symptoms, the maincharacteristic is that surface has obvious lesions, softening and bouffant, local skin andmuscle tissue inflamed, it similar to other fish boils disease. Liver and Kidney are swelling,bleeding, severe generalized cell damage, necrosis, caused the body organs, especially led toliver and kidney dysfunction and failure, eventually the body defense mechanism collapsedand died of sepsis.Through to common drug sensitivity analysis13isolates what are isolated from sick fishtissue and has been identified as the pathogenic Aeromonas hydrophila, we know that:13strains of bacteria to penicillin G, levofloxacin, doxycycline and ciprofloxacin are highlysensitive or moderately sensitivity with basically identical. It is proved by practice that theseseveral antibiotic treatment effect is better; And the resistance test of many strains of bacteriaisolated from Pike show obvious differences.