Diagnosis Of Motile Aeromonas Sobria From Cat Fishes With Septicemia By PCR

Aeromonas septicemia is a life threatening bacterial infection in fishes, concurrently in human with weakened immune systems. Present research work aims to isolate and identify the virulent strains of motile Aeromonas species linked with the septicemia in 12 fresh water cat fishes (Clarius batrachus) in the locality of Sathyamangalam, Tamil Nadu. A total of 72 samples consisting of intestinal contents, spleen, kidney, gills, liver and skin were collected aseptically from the infected cat fishes. Upon detailed bacteriological investigation, 56(77.78%) isolates were tentatively identified as A. sobria. All these isolates were further screened for hemolysin gene (ahh1), A. hydrophila aerolysin gene (area), A. sobria hemolysin gene (asa1) and A. caviae hemolysin gene (cav1) by polymerase chain reaction. In PCR, 43(76.78%) of 56 isolates, were found positive for single asa1 gene, while, 3(5.35%) were also positive for both asa1 and ahh1 genes. None of the isolates were positive for aerA and cav1 genes. PCR result suggested the presence of virulence genes in 46(82.14%) isolates of A. sobria. The asa1 gene has proven to be the predominant virulence factor in A. sobria associated with Aeromonas septicemia in cat fish. PCR based identification of virulent strains of A. sobria appeared to be very useful, sensitive and less time consuming method than traditional microbiological identification system.