Antibacterial activities of the plant extract of Alternanthera repens

Aims: Plants have been described as gift of nature and they have been utilized as a therapeutic agent against various infectious diseases affecting both human and animals. This present study is aimed at determining the antibacterial efficacy of the methanol plant extract of Alternanthera repens against some clinical bacterial isolates. Methodology and results: Methanolic extract of the plant A. repens was obtained using the cold method of extraction. The bioactivity of the extracts was tested against bacterial isolates namely: Staphylococcus aureus, Streptococcus faecalis, Escherichia coli, Bacillus subtilis, Bacillus cereus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, and Proteus mirabilis. The agar well diffusion method was used for the in vitro antibacterial bioassay and it revealed that the extract was able to inhibit the growth of the test organisms at a concentration of 25.0 mg/mL except E. coli, S. faecalis and S. typhi, with the highest zone of inhibition (30 mm) observed on S. aureus. The minimum inhibitory concentration (MIC) of the plant extract ranged from 25.0 to 3.125 mg/mL. The antibacterial activity of the methanolic plant extract compared favourably well with commercial antibiotics. The rate of killing of the plant extract on the isolates showed a decrease in the bacterial count with an increase in the exposure time. Phytochemical screening tests showed the presence of saponins, alkaloids, salkowski, and keller killianie in the plant extract. Conclusion, significance and impact study: A. repens has wound and urinary tract infection healing property as observed from its antibacterial effect against some of the implicating organisms. Its usage can thus serve as an alternative means of cost effective treatment of infections in covering the basic health needs of people in developing countries.