Pathogenicity of the bacterial isolate Aeromonas hydrophila to catfishes, carps and perch

Abstract

Pathogenicity of a bacterial isolate Aeromonas hydrophila recovered from naturally diseased shing fish was investigated against catfishes (Heteropneustes fossilis and Clarias batrachus), carps (Labeo rohita, Catla catla and  Cirrhinus cirrhosus) and perch (Anabas testudineus) of average body weight of 20.4 g for H. fossilis, 25.6 g for C.  Batrachus, 35.2 g for L. rohita, 25.7 g for C. catla, 30.5 g for C. cirrhosus and 20.3 g for A. testudineus. Two different  doses viz. 6.7 × 10⁶ and 6.7 × 10⁵ CFU/fish were injected intramuscularly. Pathogenicity of A. hydrophila was confirmed at water temperature of 30°C by mortality of 60% to 100% of all the tested fishes within 2-11 days. Injected  A. hydrophila was re-isolated from liver, kidney and intestine of all the tested fishes. The highest bacterial loads in catfishes were found to be 5.5 × 108 CFU/g in the liver of H. fossilis and 5.6 × 10⁷ CFU/g in the intestine of C.  batrachus. The lowest bacterial loads were found to be 2.2 × 10² CFU/g in the kidney of H. fossilis and 2.4 × 10³ CFU/g in the liver of C. batrachus. The highest bacterial loads in carps were found to be 4.9 × 10⁹ CFU/g in the liver  of C. catla, 7.7 × 10⁸ CFU/g in the intestine of L. rohita and 5.8 × 10⁸ CFU/g in the intestine of C. cirrhosus. The   lowest bacterial loads were found to be 2.7 × 10⁴ CFU/g in the kidney of C. catla, 3.0 ×10⁴ CFU/g in the kidney of L   rohita and 5.6 × 10³ CFU/g in the kidney of C. cirrhosus. The highest and lowest bacterial load in perch was found to  be 6.4 × 10' CFU/g and 1.6 × 10² CFU/g in the intestine and kidney of A. testudineus respectively. In all the cases of  intramuscular injection, external pathology was found. Reddish anal region and fm bases were observed. It was   understood that the isolate was a highly virulent pathogen for the challenged fishes.

DOI: http://dx.doi.org/10.3329/jbau.v10i1.12108

J. Bangladesh Agril. Univ. 10(1): 157161, 2012