مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

From the winter 2002 to spring 2006, )26 moribund rainbow trout with clinical signs of external body haemorrhages around and within the oral cavity were sampled from 10 rainbow trout farms situated in the northwest and west of Fars province, Iran and examined for the detection and identification of Yersinia ruckeri, the causative agent of enteric redmouth disease. Fish kidneys were cultured aseptically on brain heart infus ion (BBI) agar plates and incubated at 25°C for 48 h. Using conventional biochemical tests, Y ruckeri was detected in 7 fish (5.5% of total fish sampled). This was also confi rmed using specific polymerase chain reaction (PCR) assay. The )6S rDNA PCR assays produced amplicons of 409 bp when applied to Y. ruckeri isolates as well as a reference strain. Results of antibiogram tests on Y. ruckeri isolates showed a high susceptibility to enrofloxacin, norfloxacin, ofloxacin, trimethoprim and oxytetracycline. In pathogenicity tests, dilution of 4 x ) 08 colony forming unit/ml of Y. ruckeri by immersion route in challenge experiments showed 70 ± 8.2% mortality during 14 days post-infection. Experimentally infected fish showed typical haemorrhages in mouth, blackeningof skin, exophthalmia anda wide haemorrhages on the internal organs.