The incidence of diseases in aquaculture production has been described as one of the greatest setbacks, characterized by financial losses with attendant environmental and public health implications. The prevalence, antibiogram, and antibiotic-resistant genes of Vibrio parahaemolyticus isolated from apparen tly healthy farmed Clarias gariepinus were assessed. A total of 285 adult fish and 39 fingerlings were analysed. Tissue samples were cultured using Thiosuifate Citrate-Bilesalts Sucrose (TCBS) media (Millipore®, Germany) and incubated at 30°C for 24 hours after which biochemical characterisation was carried out for detailed identification. Nineteen (19 ) representative isolates were selected for Antibiotic Sensitivity Test (AST), and Antibiotic Resistant Genes (ARGs) determination through whole-genome sequencing.
A total of two hundred and seven (207) Vibrio parahaemolyticus organisms were isolated, which translated to 39.8% and 47.7% prevalence in Delta and Ogun states, respectively . All the Vibrio parahaemolyticus isolates showed 100% sensitivity to tetracycline and florfenicol, 81.8%/87.5% to chloramphenicol and streptomycin, 72.7%/62.2% to ampicillin, and 63.6%/87.5% to Trimethoprim/Sulfamethoxazole in both states, respectively. The isolates had 72.2% sensitivity to kanamycin in Delta State. 100% resistant to Novobiocin, 90.9%/50% to terramycin, 81.8%/87.5% to Nalidixic acid and Nitrofurantoin, 81.8%/75% to Colistin sulphate respectively, and also resistant to kanamycin (62.5%) in Ogun State. The multiple antibiotic resistance index (MARI) ranges between 0.16 and 0.67. The whole-genome sequencing revealed the presence of twenty-five antibiotic resistance genes covering aminoglycosides, beta-lactamases, chloramphenicol, trimethoprim, florphenicol, fosfomycin, quinolones, fluoroquinolones, streptothricin, sulphonamides, and tetracycline.
The prevalence, multi-drug resistance status, and acquisition of a large number of antibiotic resistance genes in aquaculture environment has public and environmental health implications for the AMU/AMR menace. The results from this study suggest a significant abuse of antibiotics, aquatic environmental pollution from hospitals and manufacturing industries . This also renders the treatment of fish diseases difficult and makes both fish and fish products unwholesome. Best management practices, treatment of effluent discharges and adequate oversight by competent authorities is hereby recommended.
Keywords: Aquaculture, Vibrio parahaemolyticus, Antibiotic Resistant Gen es, Clarias gariepinus , Biosecurity , AMU/AMR