ABSTRACT
Pseudomonas fluorescens [Ps. fluorescens] strains recovered from diseased Oreochromis niloticus [O. niloticus] were studied for their pathogenicity, scrum resistance activities and serological relatedness. The results of experimental pathogenicity in O, niloticus varied and generally ranged from acute septicaemic course to mild slow developing one or even none, suggesting the existence of variable virulence profiles among Ps. fluorescens strains. A correlation was found between serum resistance activity of Ps. fluorescens strains and their corresponding degrees of pathogenicity and virulence profiles as proved by the presence of a shared common resistance to the killing effect of O. niloticus serum among the highly pathogenic virulent strains. In addition, heterogenecity among Ps. fluorescens strains was biochemically and sero logically proved
Subject(s)
Animals , Tilapia/microbiology , Fish Diseases/bloodABSTRACT
Vibrio species were recovered from 40.00% of examined fish in both Qarun and Manzala lakes. The isolation was 37.50% from Mugil cephalus and 42.50% Oreocliroinis niloticus. Recovered Vibiros were V. anguillarum biotype c, V. ordalii, V. damsela and V. vulnificus group 2. A concentration of 4-9% sodium chloride in the culture media was helpful in the isolation of Vibrio species. Septicaemic picture of intraperitoneally inoculated Oreochromis nhloticus with different Vibrio species occurred within 1-week post - infection. Active immunization of O. niloticus with formalized whole cultures prepared from recovered vibrios resulted in diferent titres with the highest recorded one against V. angullarurn biotype C. serological relatedness among different vivrios and their corresponding antisera showed that antisera of V. anguillaruni biotype C was able to cross react with other vibrio species. Sensitivity of recoverd vibrios was recorded to chioramphenicol, colistin sulphate, nitrofuratntion, oxytetracycline and tetracycline