A Trial to detect Pathogenic behaviour of members of genus Aeromonas Isolated Form Fish by using DNA Manipulation

The aim of investigation was applied to detect andcharacterize virulence factors among Aeromonas speciesisolated from diseased Oreochromis niloticus by usingdifferent methods specially DNA methods.Two hundred of diseased fish were subjected to fullclinical, post- mortem and bacteriological examinations.The clinical signs of diseased fish were noticed suchas haemorrhagic septicaemia all over the body of fishspecialy at the end of fms, fin rot, scale loss, skin ulcers,abdominal ascitis, corneal opacity in one or two eyes,inflammations at the end of vent and all the internal organswere found to be congested.from the bacteriological investigation for naturallyinfected fish, the following bacteria were isolated A.hyDROPhila, A. sobria, A. caviae, Pseudomonas group andEnterobacter group.In this study, the total prevalence of Aeromonas spp.infection among the examined Oreochromis niloticus was65%. A. hyDROPhila was the highest incidence (40 %)followed by A. sobria (17.5 %) and A. ea viae (7.5%) whichdifferentiated between them by some bacteriologicalexaminations such as M. R. and some sugars as esculine,arabinose and salicine.Nine Aeromonas spp. isolates (3 A. hyDROPhila, 3 A.sobria and 3 A. caviae) were randomly selected and tested