Isolation and characterization of antibiotic resistant bacteria from selected fish farms in the Central and Western Regions of Ghana

Abstract

The study sought to investigate antibiotic resistant bacteria from fish farms in the Central and Western regions of Ghana. Management practices and antibiotic use at the fish farms were obtained through questionnaire. Bacterial loads of catfish (Clarias gariepinus), tilapia (Oreochromis niloticus), and pond water samples recovered on MacConkey Agar and Mannitol Salt Agar were determined. Bacterial isolates were identified using biochemical assays. Antibiotic resistance profile and resistant genes of isolates were determined using disc diffusion method and Polymerase Chain Reaction technique respectively. The study revealed that none of the selected farms made use of antibiotics for prevention and treatment of diseases and no major disease outbreak had ever been recorded. Bacterial loads of pond water and fish samples exceeded the acceptable level of ≤100 E. coli and <10 coliforms per mL for wastewater recommended for use in fish farming and 5×105CFU/g for fresh fish regarded as wholesome. Total of 145 bacterial isolates consisting of 99 (68.30%) coliforms and 46 (31.70%) Gram-positive bacteria were obtained. All isolates showed resistance to at least an antibiotic except Edwardsiella tarda. Both coliform and Gram-positive bacteria were highly resistant to betalactams with corresponding high detection of TEM gene compared to other classes of antibiotics. This study has demonstrated that antibiotic resistant bacteria are present at the fish farms and might have been introduced into the fish farms from the environment where antibiotics are regularly used. Education on risks associated with the use of antibiotics and its impact on bacteria in the environment needs to be intensified.