Abstract:
The antibacterial efficacy of leaf extracts from guava Psidium guajava (Linn) were assessed on bacterial indicators isolated from two groundwater sources that are prone to faecal contamination in Akure, Nigeria. The load of faecal bacterial indicators in the water samples were determined using standard microbiological methods. Physicochemical characteristics of the water samples were determined using standard methods. The antibacterial effects of leaf extracts P. guajava on the isolated organisms were determined using agar well diffusion method. The screening for the phytochemical constituents of the leaf extracts of P. guajava were determined using standard methods. Antibiotics sensitivity testing was carried out using disks diffusion method. Plasmid profiling, and curing of antibiotics resistant isolates were determined using gel electrophoresis and Sodium dodecyl sulfate. Results revealed that the load of faecal coliforms ranged from 2.70 to 4.46 log10 CFU/100 ml in water sample A and from 2.95 to 4.50 log10 CFU/100 ml in water sample B and Escherichia coli ranged from 2.30 to 3.51 log10 CFU/100 ml in water sample A and from 2.60 to 3.52 log10 CFU/100 ml in water sample B. The values of pH ranged from 6.73 to 7.64 in water samples A and from 6.80 to 7.55 in water samples B. The ethanol leaf extracts of P. guajava exhibited the highest zone of inhibition (22 mm) at 200 mg/ml concentration and the lowest zone of inhibition (7 mm) at 25 mg/ml on E. coli. However, no zone of inhibition of leaf extracts of P. guajava was observed on Salmonella spp. The phytochemical constituents revealed the presence of bioactive compounds such as saponin and flavonoid. The antibiotics sensitivity testing revealed that Salmonella spp showed significant resistance to all antibiotics except ciprofloxacin. The findings from this study demonstrated that ethanol leaf extracts of P. guajava (LINN) exhibited antibacterial efficacy on E. coli and Shigella spp isolated from water samples from selected groundwater sources in Ipinsa, Akure, Nigeria.
