ABSTRACT
The occurrence and distribution of multiple resistant bacteria in Ikpoba river backwater in Benin city have been investigated in this study. Water samples (n=6) were collected from three different stations along the course of the river. Samples were transported to the laboratory for both physicochemical and microbiological investigations. Physicochemical analyses involved assay for levels of pH, suspended solids, salinity, total hardness, electrical conductivity, turbidity, phosphate, nitrate and sulphate. Bacteriological analysis was conducted to identify bacteria isolates present in the water samples collected from the river. Phenotypic virulence factors of the isolates were investigated using haemolysis production tests (Blood agar plates, lipase activity, DNA degrading activity). Biochemical tests such as catalase, indole, oxidase, citrate, KOH, sugar fermentation test were also conducted. The antimicrobial susceptibility testing of the various isolates were investigated using Kirby-Bauer disk diffusion method. Multiple antibiotic resistance test was evaluated from the zones of inhibition obtained from the antibiotic susceptibility test. Results from the study revealed the range values of physicochemical parameters as pH (4.04±0.00 – 4.11±0.01), salinity (177±0.58 -181±0.00mg/L), temperature (25.00±0.00 -25.50±0.00oC), electrical conductivity (353±0.58 – 361.67±0.33mg/L), suspended solids (0.48±0.05 – 0.58±0.43mg/L), turbidity (1.01±0.01 – 1.21±0.89 NTU), nitrate (0.23±0.05 – 0.43±0.33mg/L), phosphate (0.05±0.01 – 0.10±0.08mg/L), sulphate (0.41±0.09 – 0.75±0.57mg/L), dissolved oxygen (0.14±0.03 – 0.25±0.19mg/L), BOD (0.01±0.01mg/L), COD (0.18±0.04 – 0.33±0.25mg/L). Biochemical test results revealed the presence of bacteria such as Escherichia coli, Salmonella sp., Enterobacter aerogenes, Pseudomonas sp. and Shigella sp. Pathogenicity test of all bacteria isolates were β-haemolytic in nature and possessed the ability to completely lyse red blood cells in blood agar indicating they all were pathogenic in nature. Spirit Blue Agar test revealed that all isolates were positive for production of lipase. The total heterotrophic bacteria count of back water samples from the Ikpoba river ranged from 3.31×102 – 3.44×102cfu/ml. The results obtained for the antimicrobial test revealed that zone of inhibition exhibited by Gentamycin, Erythromycin, Clindamycin, Augmentin, Carbenicillin, Ciprofloxacin, Colistin and Tetracycline ranged from 1-10mm, 1-5mm, 2-4mm, Nil, Nil, 5-16mm, Nil and 1-2mm respectively. The bacteria isolates exhibited resistance to some of the test antibiotics. The presence of multiple antibiotic resistant bacteria isolates in the water samples is of great concern. Further studies is paramount in monitoring the microbial safety of surface water bodies so as not to lead to water borne diseases which might possess threat to humans.
