Efficacy of leaf extracts of Psidium guajava (L.) on enteric bacterial isolates from faecally impacted groundwater

Abstract

The efficacy of leaf extracts of guava Psidium guajava (L.) were assessed on enteric bacteria isolated from two wells (W1 and W2) prone to faecal contamination in Akure, Nigeria. The load of enteric bacteria in the water samples was determined using a standard microbiological method. Leaf extracts of P. guajava (L.) were prepared using ethanol and hot distilled water and the antibacterial effects of the extracts on bacterial isolates were determined using the agar well diffusion method. Phytochemical components of the leaf extracts were carried out using standard methods. Results revealed the following mean concentrations of enteric bacteria in W1 and W2: Salmonella (3.8 and 3.9 log10 CFU/100 ml) and Shigella (3.6 and 3.7 log10 CFU/100 ml). The ethanol leaf extracts of P. guajava (L.) exhibited a zone of inhibition of 22 mm at 200 mg/ml on Shigella and no zone of inhibition was observed on Salmonella. The phytochemical components of ethanol and hot distilled water leaf extracts of P. guajava (L.) revealed the presence of saponin as (13.64 mg/g) and (59.82 mg/g). The findings of this study revealed that ethanol leaf extracts of P. guajava (L.) may be useful as an antibacterial agent against Shigella. HIGHLIGHTS The level of faecal pollution in the wells was 'critical' based on E. coli concentration.; Hot distilled water leaf extracts of guava had no effect on Salmonella and Shigella.; Resistance of Salmonella was plasmid-based.; Bioactive components of ethanol leaf extracts of P. guajava contributed to the antibacterial effect on Shigella.; Antibacterial potential of P. guajava leaves may be enhanced by extracting with ethanol.;

Keywords

• diarrhea
• enteric bacteria
• groundwater
• inhibition
• leaf extracts
• phytochemical components