Identification and Antimicrobial Sensntivity Studies of Aeromonas Species Associated with Bacterial Septicemia of Esox lucius in Xinjiang, China

Abstract

This study aimed to investigate the incidence of Esox lucius with bacterial septicemia in five fish ponds of Xinjiang, China. We analyzed the water quality of each fish pond as well as the clinical symptoms and pathological changes of fish with bacterial septicemia. Furthermore, we isolated and identified pathogenic bacteria from the liver, spleen, and kidney of the infected fish based on morphology and physiology, as well as using biochemical and molecular biology techniques. By detecting the water quality of the infected fish pond, the clinical symptoms and pathological changes of the infected fish were observed, pathogenic bacteria were isolated and purified from the liver, spleen, and kidney of the died illness fish. the pathogenicity of pathogenic bacteria was identified by morphology, physiology, biochemistry, and molecular biology, and the drug sensitivity of 16 antibiotics was studied by standard Kirby–Bauer disk diffusion method. The results showed that bacterial septicemia of Esox lucius occurred in water with high levels of ammonia nitrogen, nitrates, pH, total alkalinity, and total hardness, mainly caused by the mixed infection of Aeromonas hydrophila, Aeromonas veronii and Aeromonas sobria. A rapid multiplex PCR method for the detection of pathogenic Aeromonas hydrophila was established. The isolates were sensitive to enrofloxacin, flufenicol, and doxycycline and resistant to penicillin and neomycin. This study laid a foundation for the early prediction, warning, rapid diagnosis, and effective prevention and control of bacterial septicemia.