RESUMO
A total of 140 rectal swabs, 20 of apparently healthy, 80 diarrhoeic rabbits and 40 freshly dead and sacrificed diarrhoeic rabbits 6-8 weeks old collected from EI-Minia and Assiut provinces. Collected samples were examined bacteriologically for prevalence and pathogenicity of clostridia. According to morphological characters and biochemical reactions. The incidence of C.perfringens and C.spiroforme were 55 [39.30%] and 10 [7.14%] respectively. There was variation between the prevalence rate of clostridia according to their general healthy condition, where was 3 [15%] in apparently healthy, 32 [40] in diarrhoeic rabbits while was 30 [75%] in dead and slaughtered diarrhoeic rabbits. For toxogenic and non-toxogenic type of C-perfringens, the incidence of toxigenic type was 45 [81.82%] while was 10 [18.18%] for nontoxigenic type. ToxIgenic type revealed that type "E" was the most predominant [71.11%], followed by type "A", "D" and "B" were [15.56%], [8.89%] and [4.45%] respectively. The pathogencity test of the isolates revealed high mortality of infected rabbits with C.perfringens type "E" reached to [75%] and [37.5%] for type "A", while reached to [62.5%] for C.spiroforme. All dead infected rabbits showed profuse watery diarrhoea and die within few first days after onset. Postmortem examination showed a varying degree of inflammation and ulcerative lesions on mucosal surface of caecum, colon and ileum while internal organs were congested and sometimes necrotic foci in liver. Sensitivity test of Clostridial strains against some antibiotics in vitro showed that, Ampcillin, Norfloxacin and Chloramphenicol were highly effective, while the strains were resistance to Streptomycin and Gentamycin