Efficacy Of Some Medicinal Plants Used In Various Parts Of Kenya In Treating Selected Bacterial And Fungal Pathogens

ABSTRACT

Medicinal plants have been used since time immemorial to treat and prevent human

ailments. WHO indicates that up to 80% of the world’s population uses traditional

medicine. Infections caused by bacteria and fungi have become a major health problem

globally accounting for over 50,000 deaths every day. It is estimated that more than 70%

of the pathogenic bacteria are resistant to at least one of the antibiotics commonly used to

treat them. Conventional drugs are expensive and have side effects. Many plants have

been used by various communities in Kenya in the treatment of bacterial and fungal

infections but they have not been validated. The main aim of this study was to determine

the efficacy of some medicinal plants used by various communities in Kenya that treat

the selected bacterial and the selected fungal diseases in man. An ethnobotanical survey

was used to select and collect plants from Mwingi North, Kisii South and Rarieda

Districts based on their use to treat infectious diseases such as skin infection, diarrhea and

many others. Crude extracts from Zanthoxylum chalybeum, Boscia angustifolia, Melia

volkensii, Zanthoxylum gilletii, Fuerstia africana, Urtica dioica, Vernonia amygdalina,

Ricinus communis, Commiphora africana, Psidia puntulata, Senna didymobotrya,

Ormocarpum trichocarpum, Sesbania sesban, Balanites aegyptiaca, Albizia coriaria,

Ficus sycomorus, Rhus natalensis and Tamarindus indica believed to contain secondary

metabolites were screened against ten microorganisms, including the bacteria:-

Salmonella typhi ATCC 19430, Escherichia coli ATCC 25922, Bacillus subtilis,

Staphylococcus aureus ATCC 25923 and Methicillin Resistant Staphylococcus aureus.

The fungal strains that were used are; Aspergillus niger, Candida albicans ATCC 90028,

Microsporum gypseum, Crytococcus neoformans ATCC 18310 and Trichophyton

mentagrophyte. The plants were screened using Kirby Bauer disc diffusion method.

Phytochemical screening was carried out to identify the presence or absence of classes of

bioactive compounds. Data was analyzed using one way ANOVA, significant means

were separated using Tukey’s test. Generally, Fuerstia africana, Zanthoxylum

chalybeum, Balanites aegyptiaca, Ormocarpum trichocarpum, Senna didymobotrya and

Tamarindus indica gave strong antibacterial results of between 14.5 mm and 20 mm as

Albizia coriaria, Ficus sycomorus, Commiphora africana Rhus, natalensis Senna

didymobotrya, Psidia puntulata, and Tamarindus indica produced strong antifungal

results of between 15.5 mm and 20.5 mm. The results of MICs and the MBCs/MFCs of

the extracts of Albizia coriaria, Ficus sycomorus, Senna didymobotrya, Psidia puntulata,

Fuerstia africana, Balanites aegyptiaca and Tamarindus indica showed a good activity

of 0.9375 mg/ml in some test cultures. Salmonella typhi ATCC 19430 and Escherichia

coli ATCC 25922 were the least sensitive bacteria while Candida albicans ATCC 90028

was the least sensitive fungus. The present study indicates that the majority of the plants

tested are an important source of antibacterial agents especially on Gram positive bacteria

(Staphylococcus aureus, Bacillus subtilis and Methicillin Resistant Staphylococcus

aureus) and antifungal agents against the dermatophytes especially Microsporum

gypseum. This study recommends that the plant extracts with good antimicrobial activity be subjected to both pharmacological and toxicological studies.