Journal of Pure and Applied MicrobiologyVol. 4 No. 2

Virulence Determinants of Aeromonas hydrophila Isolated form Aeromonas septicemia

A. Lakshmanaswamy1, M. Karthikeyan2, A.C. Kiruba Shankari1, Nancy Sylviya S. Christina1, N.S. Vasanthi1 and Arunava Das1*

Department of Biotechnology, Bannari Amman Institute of Technology, Sathyamangalam - 638 401, India. 2Eurofins Genomics India Pvt Ltd, Whitefield, Bangalore - 560 066, India.

Received on 30 March 2010 and accepted on 08 May 2010



The study reports the diagnosis of motile Aeromonas septicemia caused by Aeromonas hydrophila isolated from two cat fish (Calarius batrachus) collected from Kodiveri Dam of Erode District, Tamil Nadu. Samples from skin, intestinal contents, kidney, liver, gills, muscle and spleen from the infected fishes were investigated for the isolation of bacteria and their virulence determinants. A total of 14 isolates of Aeromonas hydrophila were identified morphologically and biochemically. All the isolates were found to be flagellated and motile. Polymerase chain reaction (PCR) revealed the presence of hemolysin (ahh1; 130bp fragment) and aerolysin (aerA; 309bp fragment) toxin genes among the isolates. However, out of 14 isolates, 11 (78.5%) isolates were positive for both ahh1 and aerA genes, and remaining 3 (21.4%) isolates were positive for only ahh1 gene. All the isolates were 100% resistance to amphicilin, clindamycin and cephalothin; moderately sensitive to colistin, cholarmphenicol and tetracycline; 100% sensitive to nalidixic acid, nitrofurantoin and cefuroxime. This study confirmed the involvement of both hemolysin and aerolysin toxins producing motile A. hydrophila associated with the septicemia in cat fishes. This study suggested that the antibiotics like nalidxic acid, nitrofurantoin and cefroxime can be effective control of A. hydrophila infection in cat fishes.

Keywords : Aeromonas hydrophila, Cat fish, PCR.