Antibacterial Activity And Toxicity Of Non-Aqueous Extract Of Bidens Pilosa Against Escherichia Coli In Female Balb/C Mice

ABSTRACT

The increase in prevalence of antimicrobial resistance in members of enterobacteriaceae is posing a major challenge in treatment of bacterial infections and paving way to emergence of multidrug resistant pathogens. Multidrug resistance pathogens such as strains of bacteria (Escherichia coli) produce extended spectrum Beta-lactamases hence are a global problem. Alternative treatment is therefore needed to cure the bacterial infections. Bidens pilosa is among the plants that have been used traditionally to treat infectious diseases across the world. It is clear that geographic factors influence the metabolic phenotype of B. pilosa hence this may impact on extract biological activity. While B. pilosa is commonly used in Maseno as a herbal remedy, its activity on E. coli has not been studied. Most of the studies have focused on in vitro antibacterial activity of plant extract, but these studies have not given any insight into the ability of the plant extracts to exert in vivo antibacterial activity. The study was designed to assess the in vivo antibacterial activity and toxicity of non-aqueous extract of B. pilosa, specifically the effect non-aqueous extract of B. pilosa on E. coli in infected Balb/C mice, the acute toxicity and sub-acute toxicity non-aqueous extract of B. pilosa extract on Balb/C mice. A randomized experimental study involving 72 animals was used. The procedures were as per the Organization Economic Development guidelines with slight modifications. To test the effect of B. pilosa extract on E. coli, four experimental groups, each consisting of 6 animals were set up as follows: placebo, infected with E. coli but no treatment, infected with E. coli and treated with B. pilosa extract, and infected with E. coli and treated with tetracycline antibiotic. Acute toxicity was tested using four experimental groups that were treated as follows: placebo (normal saline), 1000mg/kg, 2000mg/kg, 4000mg/kg of B. pilosa extract once and observed for 14 days for signs of toxicity. A similar set up was used for sub-acute test except that treatment groups involved, placebo (normal saline), 1000mg/kg, 2000mg/kg and 3000mg/kg daily doses of B. pilosa extract daily for a 28 days period. One way ANOVA with Tukey post hoc tests was used for comparison whether the extract had an effect on the number of viable E. coli and mean weight comparisons. Treatment with B. pilosa reduced the number of E. coli significantly in the experimental period (p=0.000). Treatment with B. pilosa extract increased body weights of the animals significantly (p=0.000) in the experimental period. There was no mortality nor signs of toxicity even at the highest dose of 4000mg/kg. Further there was no significant difference in mean organ weights or architecture of the selected organs between the placebo and treated groups. In sub-acute toxicity test, there was a reduction of body weights (p=0.001) in animals treated with B. pilosa as well as mortality at 3000mg/kg at day 28. Treatment with the extract had no effect on body weights or mortality over the period on lower concetrations. The extract of B. pilosa demonstrated in vivo antibacterial activity against E. coli. The extract of is safe when exposed once to the experimental animals and LD50 is higher than 4000mg/kg. The extract is safe at low concentrations (1000mg/kg) but unsafe at higher concentrations when it accumulates in the body for 28 days. The study has shown that the plant possesses in vivo antibacterial activity against E. coli. The extract is safe for use at lower concetrations but can cause toxicity at 3000mg/kg over prolonged period of usage. The results obtained have confirmed its traditional usefulness in treatment of infectious diseases.