PHYTOCHEMICAL ANALYSIS AND IN VITRO ANTIMICROBIAL ACTIVITIES OF THREE MEDICINAL PLANTS AGAINST STAPHYLOCOCCUS AUREUS, CANDIDA ALBICANS AND ASPERGILLUS SPECIES ISOLATED FROM BOVINE CLINICAL MASTITIS CASES IN THE HARAMAYA DISTRICT

Abstract

The development of drug resistance to conventionally used antimicrobial agents have become significant in dairy cows due to indiscriminate use of antibiotics. Commonly used medicinal plants could serve as an alternative to the livestock owners in the treatments of infectious disease like bovine mastitis. Particularly, in eastern Hararghe of Ethiopia, various researchers have reported selected three medicinal plants used as ailments of bovine mastitis. Majority of the plants are popular and known to be utilized for the treatments of different livestock diseases including mastitis. Although traditional healers in Ethiopia have a long history of using medicinal plants to treat diseases in animals and humans, experimental studies on the antibacterial and antifungal activities of most medicinal plants are limited. Searching for alternative medicines, particularly traditionally used medicinal plants is important, because there is rapid emergence of antimicrobial resistant strains. Therefore, this study was aimed to evaluate the in-vitro antibacterial and antifungal activities of methanolic extracts of three medicinal plants namely: Clerodendrum myricoides, Anethum graveolens and Ricinus communis against S. aureus, C. albicans and Aspergillus species isolated from bovine clinical mastitis and laboratory reference strains of respective test isolates. Crude leave extract solutions were prepared at three concentrations (880mg/ml, 440mg/ml and 220mg/ml) using distilled water. Agar disc diffusion method was employed to determine antibacterial and antifungal activity by the measuring the diameter (mm) zone of growth inhibition (mean ± standard error of the mean). The minimum inhibitory, bactericidal and fungicidal concentrations were determined through broth serial dilution methods. All experiments were done in triplicate. Mean differences between the concentration of each plant and the positive control (antibacterial and antifungal drugs) were analyzed using one-way ANOVA at 0.05 significant level (95% CI). The study findings recorded were higher zone of inhibition on S. aureus (with 14.33 ± 0.3mm), C. albicans (with 23 ±1.12mm) for C. myricoides and on Aspergillus flavus (with 17.3 ± 0.3 mm), Aspergillus niger (with 19.67 ± 0.3 mm) for A. graveolens. C. myricoides showed MIC on S. aureus (with 45.8 ± 9.2mg/ml), C. albicans (with 36.7 ± 9.2mg/ml) and A. graveolens on Aspergillus species (with 73.3 ± 18.3mg/ml). C. myricoides showed MBC/MFC (with 220mg/ml) on S. aureus and C. albicans and A. graveolens (with 366.7 ± 73.3mg/ml) on Aspergillus isolates. This study indicated that potential antibacterial and antifungal effects of xiv all extracts against clinical and standard strains of tested S. aureus and C. albicans, whereas A. graveolens was the only crude extract active against Aspergillus isolates. As interpretations of this study C. myricoides extract showed the highest promising anticandidal activity with significant (p<0.05) superiority than the positive control (Fluconazole). Therefore, in-vivo antimicrobial study should be conducted to confirm the in-vitro antibacterial and antifungal activities of crude extracts against selected isolates as well as to elucidate the safety of test plants on their use as intramammary infusions