Thong tin chung:

Ngay nh?n bai: 08/08/2018

Ngay nh?n bai s?a: 06/10/2018

Ngay duy?t dang: 26/04/2019

Title:

Isolation, identification and characterization of Aeromonas schubertii causing internal white spot on snakehead fish (Channa striata) in the Mekong Delta of Vietnam

T? khoa:

Aeromonas schubertii, c?m nhi?m, Channa striata, mo b?nh h?c

Keywords:

Aeromonas schubertii, Channa striata, histopathology, infection

ABSTRACT

The bacterium Aeromonas schubertii, was isolated and identified as the aetiological agent causing internal white spot disease in snakehead fish (Channa striata) suffering from high mortality rates within hatchery and commercial farms in 4 provinces: Tra Vinh, An Giang, Dong Thap and Dong Nai. A total of 192 diseased specimens showing white-spot in internal organs was collected from 53 different farms. The typical clinical signs were observed the presence of whitish nodules in the liver, spleen and kidney. The bacteria were isolated with tiny pale yellow colonies on tryptic soya agar after incubating at 28?C for 24-36 hours, and were analyzed as negative Gram and short rod-shaped, motile and oxidase positive. A combination of conventional biochemical tests, API 20E system and 16S rRNA gene partial sequencing was used to identify the all isolates as Aeromonas schubertii. An experimental injection challenge study was performed and fulfilled Koch?s postulates with LD₅₀ values of 6.59x10³ and 8.12x10³ cfu per ml. Histological examination was found numerous multifocal granulomas in internal organ tissues: liver, spleen and kidney.

TOM T?T

Vi khua?n Aeromonas schubertii d??c phan l?p va d?nh danh la tac nhan gay b?nh d?m tr?ng n?i t?ng tren ca loc (Channa striata) gay thi?t h?i nghiem tr?ng v?i t? l? hao h?t cao trong cac tr?i gi?ng va ao nuoi tham canh ? 4 t?nh nh?: Tra Vinh, An Giang, D?ng Thap va D?ng Nai. T?ng s? 192 m?u ca loc b?nh d?m tr?ng n?i t?ng d??c thu t? 53 ao nuoi khac nhau. Da?u hie?u be?nh ly? d?c tr?ng co cac d?m tr?ng nh? ? gan, th?n va t? t?ng. Tren moi tr??ng TSA, vi khua?n co khu?n l?c nho? mau vang nha?t, sau 24-36 gi? ? ? nhi?t d? 28?C, va la vi khu?n Gram am, hinh que ng?n, di d?ng va oxidase d??ng tinh. D?a vao d?c di?m hinh thai, sinh ly, sinh hoa, kit API 20E va k?t qu? gi?i trinh t? gen 16S rRNA, vi khu?n nay d??c xa?c di?nh la loa?i Aeromonas schubertii. Thi nghi?m c?m nhi?m b?ng ph??ng phap tiem cho th?y vi khu?n co kh? nang gay b?nh v?i d?u hi?u b?nh ly gi?ng nh? ngoai ao nuoi, v?i gia tr? LD₅₀ c?a hai ch?ng vi khu?n thi nghi?m la 6,59x10³ CFU/mL va? 8,12x10³ CFU/mL, k?t qu? nay th?a m?n v?i d?nh d? Koch. K?t qu? ki?m tra mo b?nh h?c d? quan sat d??c cac u h?t v?i nhi?u hinh d?ng khac nhau ? m?u mo gan, th?n va t? t?ng.

Trich d?n: T?? Thanh Dung, Le Minh Khoi va? Nguye?n Ba?o Trung, 2019. Phan la?p, di?nh danh va? da?c die?m c?a vi khua?n Aeromonas schubertii gay b?nh d?m tra?ng no?i ta?ng tren ca lo?c (Channa striata) ? D?ng b?ng song C?u Long. T?p chi Khoa h?c Tr??ng D?i h?c C?n Th?. 55(2B): 69-78.