Composition, distribution and antibiotic sensitivities of bacteria associated with cultured Clarias gariepinus (Burchell 1822)

Abstract

The heterotrophic bacteria of African catfish, Clarias gariepinus at fingerlings and adult stages of growth were quantitatively and qualitatively examined. Methodology and results: Bacteriological analysis was carried out on sampled organs (skin, gills, and intestines) of fingerlings, adult fish, and their respective culture environments (water and sediments) by standard microbiological techniques. Sensitivity of the isolated bacteria to antibiotics were also determined. The total bacterial counts in fingerlings skin ranged from 1.3±0.3×103 to 5.4±2.3×103 cfu/cm2; gills, 3.8±1.6×103 to 1.1±0.4×105 cfu/g; intestines, 3.5±2.2×105 to 5.4±4.3×106 cfu/g and fingerlings culture water, 1.5±0.8×103 to 2.9±1.6×103 cfu/mL. The sediments of adult fish had higher bacterial loads (1.5±0.7×105 to 2.4±1.4×106 cfu/g) than that of water (3.4±0.6×103 to 8.4±4.2×103 cfu/mL), skin (4.8±1.4×103 to 3.4±1.4×104 cfu/cm2) and gills (6.6±1.3×103 to 3.5±2.0×104 cfu/g). In all, fourteen bacteria genera were identified which were predominantly Gram negative rods (Aeromonas, Alcaligenes, Chromobacterium, Citrobacter, Enterobacter, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella and Serratia). Some Gram positive bacteria (Micrococcus, Staphylococcus, Streptococcus and Bacillus) were also identified. The isolated organisms showed high level of sensitivity to Ciprofloxacin, Perfloxacin and Gentamicin with moderate sensitivity to Amoxicillin, Erythromycin, Tetracycline and Streptomycin, but were resistant to Ampicillin and Zinnacef. Conclusion, significance and impact of the study: Ciprofloxacin, Perfloxacin and Gentamicin could be used in reduction of heterotrophic bacteria of C. gariepinus.