Comparative Assessment of Antibacterial Activity of Chromolaena odorata Leaf Extracts against Selected Clinical Bacterial Isolates

Abstract

Aim: This research is aimed to compare the antibacterial activities of Chromolaena odorata leaf extracts and some commonly used antibiotics against selected clinical bacterial isolates. Place and Duration of Study: The study was conducted at the microbiology laboratory of the Nigerian Institute of Leather and Science Technology, Zaria between June and September, 2016. Methods: The plant extracts were obtained using the cold extraction method and were concentrated by heating in water bath at 90°C for 48 hours. The identities of bacterial isolates collected were confirmed by standard biochemical methods. The plant extracts and bacterial isolates were stored at 4°C until required for use. The susceptibility of the bacteria to extracts was tested using the agar well diffusion method while the modified Kirby Baur agar discs diffusion method was used for the antibiotics susceptibility test. The antibiotics activity was subjected to MAR index analysis and the results noted. Results: The results of this study showed that water had significantly higher percentage yield (13.21%) compared to the other extraction solvent (ethanol) with the yield of 10.45%. The results of our study indicated that the ethanolic extract was more effective in comparison with the aqueous extract. Although at 125 mg/mL, the both extracts were able to inhibit the growth of majority of bacteria tested. The antibiotic susceptibility profile analysis indicated that Proteus mirabilis and Pseudomonas aeruginosa had high level resistance to some of the tested antibiotics whereas Bacillus subtilis was resistant to only one of the tested antibiotics. Streptomycin was most active whereas Ofloxacin was less active. All the bacteria except Bacillus subtilis had MAR index of ≥ 0.2. Bacillus subtilis had 0.1. Conclusion: The findings of this study show that Chromolaena odorata leaf extracts possess a good antibacterial activity against the tested bacteria. It is clear from this study that most of the pathogens were resistant to the tested antibiotics but susceptible to the plant extracts although at high MIC and MBC.