Aeromonas hydrophila: Antimicrobial susceptibility and histopathology of isolates from diseased catfish, Clarias gariepinus (Burchell)

Abstract

Antimicrobial resistance in bacterial pathogens is a global public health problem. The aim of this research was to reveal the distribution and antimicrobial drug resistance of bacterial pathogens in diseased catfish, Clarias gariepinus (Burchell) from Marang River Terengganu, Malaysia. Eleven isolates of Aeromonas hydrophila were derived from diseased fish. Commercial biochemical identification kit (BBL-Crystal) and the PCR products of 16S rDNA was used to identify the isolated bacterial strains. Disc diffusion method using 6 types of antibiotic discs was performed for antibiotics susceptibility testing. The majority of isolated bacteria were A. hydrophila. All isolates of A. hydrophila were resistance to Ampicillin and susceptible to tetracycline of the analyzed isolates against the tested antibiotics. Multiple drug resistance index (MAR) for all isolates was ranged from 0.10 to 0.50. Isolates of A. hydrophila showed β- haemolytic pattern on blood agar. Clinically; exophthalmia and dermal lesions with hyperaemia and cellulites of the fins were observed. Necropsy revealed yellow foci on the liver surface, tightly full gall bladder with emerald green bile and swollen, friable kidney and spleen. Histopathologically indecated skin necrosis, hyperplasia in the secondary lamellae of gill, degenerative changes in glomerular epithelium in kidney, vacuolar degeneration in hepatocytes, hyperplasia in the lymph follicles of spleen, edema, and focal hyaline degeneration in muscles. Therefore, routine monitoring of drug susceptibility pattern over time is necessary. © 2013 Laith AR, et al.