Kajian patogenisitas bakteri Edwardsiella ictaluri pada ikan patin Pangasionodon hypophthalmus

ABSTRACT One of major problem of striped catfish Pangasionodon hypophthalmus culture is enteric septicemia of catfish (ESC), bacterial disease of Edwardsiella ictaluri , caused of more than 50% of mortalities. This reaserch was aimed to determine pathogenicity of local isolate E. ictaluri . Thirty individu of five group fishes, 6–10 g in body weight, injected intraperitoneally with 0,1 mL of bacteria suspension of 10 2 cfu/mL; 10 4 cfu/mL; 10 6 cfu/mL; 10 8 cfu/mL; 10 10 cfu/mL; and PBS as control, were culture in 18 of 60×40×45 cm 3 aquarium for seven days. External organs of fish (skin and abdomen) and internal organs (liver, kidney, and brain) were examined macroscopicly and microscopicly. Internal organ sample were taken on the 5 th day for histopatologic test while blood sample was on the 1 st , 3 rd , and 5 th day after infection. Mortality rate was count to reach LD50. Clinical signs and pathology anatomy of co-infection fish showed vertical swim, petechial hemorrhage in the skin, dropsy, ascites in the abdominal cavity, pale liver and the kidney was dark red. Histopathology showed hydropic degeneration, fatty degeneration, hemorrhage and necrosis in the liver, melano macrophage center (MMC) and necrosis in the kidneys, hemorrhage, and inflammatory cell infiltrates were also found in the kidneys and brain. Decreased of hematocrit and hemoglobin values of all tread group were statistically significant different (P 50%. Penelitian ini dilakukan untuk mengetahui patogenisitas E. ictaluri isolat lokal pada ikan patin. Masing-masing 30 ekor ikan patin ukuran 6–10 g/ekor diinjeksi secara intraperitoneal dengan 0,1 mL larutan bakteri kepadatan 10 2 cfu/mL; 10 4 cfu/mL; 10 6 cfu/mL; 10 8 cfu/mL; 10 10 cfu/mL; dan PBS sebagai kontrol. Ikan dipelihara selama tujuh hari pada akuarium berukuran 60×40×45 cm 3 . Pemeriksaan makroskopis dan mikroskopis dilakukan terhadap organ eksternal (kulit dan abdomen) dan internal (hati, ginjal, dan otak). Pengambilan sampel organ internal untuk uji histopatologi pada hari kelima dan sampel darah untuk uji gambaran darah pada hari pertama, ketiga, dan kelima pascainfeksi. Jumlah kematian ikan dihitung untuk mendapat nilai LD50. Pengamatan gejala klinis dan patologi anatomi ditemukan ikan berenang vertikal, adanya bercak merah pada kulit, pembengkakan abdomen, asites, hati pucat, dan ginjal berwarna merah kehitaman. Hasil histopatologi terlihat terjadinya degenerasi hidropik, degenerasi lemak, melano macrophage center (MMC), nekrosa, hemoragi, dan infiltrasi sel radang pada hati, ginjal, dan otak. Penurunan nilai hematokrit dan hemoglobin pada perlakuan secara statistik berbeda nyata (P<0,05) dengan kontrol. Dosis LD50 didapat 2,8×10 4 cfu/mL. Hasil penelitian ini mengindikasikan bahwa E. ictaluri pada ikan patin bersifat sangat patogen. Kata kunci: Edwardsiella ictaluri , enteric septicemia of catfish (ESC), patogenisitas, patin