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

Aims: 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±0.3x10^3 to 5.4±2.3x10^3 cfu/cm^2; gills, 3.8±1.6x10^3 to 1.1±0.4x10^5 cfu/g; intestines, 3.5±2.2x10^5 to 5.4±4.3x10^6 cfu/g and fingerlings culture water, 1.5±0.8x10^3 to 2.9±1.6x10^3 cfu/mL. The sediments of adult fish had higher bacterial loads (1.5±0.7x10^5 to 2.4±1.4x10^6 cfu/g) than that of water (3.4±0.6x10^3 to 8.4±4.2x10^3 cfu/mL), skin (4.8±1.4x10^3 to 3.4±1.4x10^4 cfu/cm^2) and gills (6.6±1.3x10^3 to 3.5±2.0x10^4 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.