ISOLATION, IDENTIFICATION AND PATHOLOGICAL LESIONS OF PSEUDOMONAS PUTIDA FROM HYBRID CATFISH

In order to identify the pathogens of the skin ulcer disease in hybrid catfish, several strains of dominant bacteria (DYJ140914-DYJ140917) were isolated from the diseased fish. They were identified as Pseudomonas putida based on morphology, biochemical, physiology characteristics and sequencing of 16S rRNA and gyrase B subunit (gyrB) gene (GeneBank accession number were KP693689 and KP693690 respectively). They were also proved to be the pathogen of the disease by artificial infection experiment. Histologically, liver, skin, muscle, and renal interstitial were the target organs of the disease, which characterized by multifocal necrotic hepatitis, necrotic myositis, and necrotizing interstitial nephritis. Moreover, it could also lead to mild epicardial and endocardial inflammation, and mild necrotic splenitis. The result of drug sensitivity test showed that the isolates were sensitive to the Doxycycline, Norfloxacin, and Levofloxacin, but were resistant to Ampicillin, Azithromycin, Florfenicol, Sinomin, Mefoxin, Penicillin.