Identification of bacterial pathogens isolated from smoked blue whiting fish (Micromesistius poutasou) from Odeomu market in Osun state Nigeria

The presence of microorganisms is one of the major factors affecting the quality of smoked fish sold in the open markets. Smoked blue whiting fish (Micromesistius poutasou), commonly called (Panla) sold in the Odeomu market in Osun State, were analyzed for microbial contaminants. Isolates were identified using conventional biochemical methods, and antibiotics susceptibility testing was carried out using the disc diffusion method. The total bacterial counts (TBC) results showed that the fish samples had high bacterial counts, ranging from 2.1×103 to 9.2×103 colony-forming units (CFU)/g. Bacteria isolated from the fish samples were: E. coli (45.46%), Enterobacter spp. (1.01%), Klebsiella spp. (6.06%), Proteus spp. (9.09%), Salmonella spp. (7.07%), Shigella spp. (19.19%), Bacillus spp. (4.04%) and Staphylococcus spp. (8.08%). The antibiotic sensitivity pattern of Gram-Negative bacteria indicated that all the isolates were resistant to more than three antibiotics. All E. coli isolates were resistant to augmentin and ceftazidime, 82.2% were resistant to cefuroxime, 17.7% to gentamicin, and 6.7% to ofloxacin. Screening of resistance genes showed that all six selected multiple antibiotic-resistant E. coli isolates tested harbored TEM gene, and two isolates (33.33%) harbored the aac (3)-II gene. None of the isolates harbored SHV, CTX-M, and qnr B genes. Our results showed that smoked blue whiting fish may pose a significant risk of spreading antibiotic-resistant bacteria that contain multiple antibiotic-resistance genes, highlighting a serious public health concern