Microbiological Assessment and Antibiotic Susceptibility of Orogodo River Exposed to Abattoir Effluent in Delta State, Nigeria

The content of abattoir effluent and its receiving water body, Orogodo River in Agbor, Delta State. Total heterotrophic and coliform counts were assessed using standard microbiological techniques. The viable heterotrophic bacteria count for the rainy season ranges from 7.7x105-4.6x104cfu/ml. Total coliform counts 2.6x105 -3.4x104 MPN/ml respectively. A total of 11 bacteria were isolated, antibiotic susceptibility pattern of bacteria was determined using the disk diffusion method. Five out of the bacteria isolates were resistant to at least four antibiotics. Out of all the antibiotics used 90 isolates were susceptible to erythromycin, 5% were resistant, also, 85 were susceptible to ofloxacin with 5% resistance and 10% were intermediate. Ampicillin had the highest resistance of 40%. The Molecular identification of multiple antibiotic-resistant bacteria was carried out using a 16S rRNA gene sequence. The identified bacteria include Shigella flexneri, Enterobacter hormaechei, Proteus vulgarus, Morganella morganii, and Pseudomonas oryzae. Data were statistically analyzed to determine the level of significance. The microbial population of bacteria isolated was found to be higher in the abattoir wastewater sample 7.7x105 and the point of entry sites 4.0x105 when compared to the downstream and upstream sample stations. The high microbial load and presence of multiple antibiotic-resistant bacteria in the river water is alarming and can lead to public health risks when such water is consumed or used for cleaning meat during processing. There is a need for proper management of abattoir waste, An on-site pretreatment strategy (collection of waste, treatment, processing, anaerobic digestion, and safe disposal) is highly recommended and should be enforced by relevant authority to safeguard the environment and the populace that depend on the Orogodo river water.