Integrated poultry-fish farming system encourages multidrug-resistant gram-negative bacteria dissemination in pond environment and fishes

Abstract A poultry-fish farming system provides an opportunity for farmers to feed fishes on a low monetary cost level by utilising poultry droppings. Wastes from poultry, majorly bird excreta, which may contain pathogenic or antibiotic-resistant bacteria, are usually released into ponds to feed fishes. This study focused on the physico-chemical analysis of pond water samples and determination of antibiotic resistance pattern of multidrug-resistant (MDR) Gram-negative bacteria isolated from poultry droppings, pond water, and fishes collected from two integrated poultry-fish farms in Osun State, Nigeria. Physico-chemical analysis of the pond water samples from the farms revealed higher levels of turbidity (farm A = 580.78 ± 297.7 NTU and farm B = 1162.25 ± 19.23 NTU), total dissolved solids (farm A = 391.9 ± 36.47 mg/L and farm B = 803.65 ± 61.26 mg/L), biochemical oxygen demand (farm A = 23.73 ± 1.24 mg/L and farm B = 28.86 ± 0.94 mg/L), chemical oxygen demand (35.59 ± 1.86 mg/L and 43.29 ± 1.46 mg/L), phosphate (farmA = 3.638 ± 0.25 mg/L and farm B = 3.54 ± 0.26 mg/L), iron (farm A = 2.64 ± 0.42 mg/L and farm B = 9.11 ± 3.48 mg/L), and manganese (farm A = 0.43 ± 0.04 and farm B = 0.66 ± 0.21 mg/L) compared to the permissible limits. Out of eighty Gram-negative bacteria isolated, 55 (68.75%) exhibited MDR phenotypes. This includes 32 (58.2%) and 15 (27.3%) bacteria isolated on both farms from poultry dropping and fish samples, respectively. The remaining 8 (14.5%) bacteria were isolated from water samples collected from farm B only. The multiple antibiotic resistance (MAR) index on both farms ranged from 0.37 to 1.00. Microbact™ 24E identified the MDR bacteria as members of the genera Aeromonas (21.82%), Burkholderia (16.36%), Pseudomonas (14.55%), Enterobacter (10.91%), Acinetobacter (9.09%), Moraxella (5.45%), Serratia (5.45%), Escherichia (5.45%), Proteus (3.64%), Citrobacter (1.82%), Stenotrophomonas (1.82%), Hafnia (1.82%) and Cronobacter (1.82%). Five of all the MDR bacterial isolates, which include Enterobacter agglomerans (n = 2), Burkholderia pseudomallei (n = 2), and Aeromonas hydrophilia (n = 1), were resistant to all the antibiotics tested. Meanwhile, four bacterial isolates, which include Pseudomonas aeruginosa (n = 2), Serratia marcescens (n = 1), and Citrobacter youngae (n = 1), were resistant to all classes of antibiotics tested. Strains of E. agglomerans, B. pseudomallei, and Aeromonas hydrophilia isolated from poultry droppings and fishes have the same antibiotype patterns. This shows the interaction between poultry and pond environments relating to the spread of antibiotic-resistant bacterial strains from poultry droppings to fish. The outcome of the study provides baseline information for future studies to understand the possible impact of integrated poultry-fish farming in matters of public health concerns such as food safety, dissemination of pathogens, and antibiotic resistance.