Effect of selected medical plant extracts against common opportunistic bacteria isolated from septic herpetic lesions among HIV and AIDS patients
Mamo, Umuro Abudo
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Opportunistic bacterial infections have been identified as a major complication in immune compromised persons. Many of the antibiotics used in management of bacterial infections are experiencing increased resistance posing enormous public health concern. Herbal extracts have in the past been found to contain antibacterial compounds. There is therefore need to continue searching for new drugs to expand the choice of compounds needed to fight these conditions. In this study, crude extracts from fifteen Kenyan medicinal plants were investigated for antibacterial activity against 60 strains of common opportunistic bacteria (Staphylococcus, Pseudomonas, Klebsiella, Proteus and Escherichia coli) isolated from confirmed HIV and AIDS patients with septic herpetic lesions. The plants were collected within Kenya and were selected from among medicinal plants widely used in the treatment of various ailments using the information obtained from ethnomedical practice and literature. Polar and non-polar solvents were employed for extraction of plants. Disc diffusion technique was used to preliminarily determine invitro antibacterial activity for the extracts by evaluating the ability of the extracts to inhibit the growth of the five bacterial species. The minimum inhibitory concentration and minimum bactericidal concentration of the extracts with the most significant predominant activity were evaluated by plate dilution method. The opportunistic bacteria were isolated using standard culture techniques and identified by colonial morphology, gram stain and biochemical test for metabolic and enzymatic reactions. The activity exhibited by plant extracts was against both gram positive and gram-negative bacteria. Of the fifteen plants screened, four extracts i.e. from Ehretia cymosa, Combretum molle, Ekerbagia capensis and Plectranthus barbatus showed significant antibacterial effects against most bacterial isolates tested. The minimum inhibitory concentration reached by 50% (MIC5o) and 90% (MIC9o) were between 0.25-lmg/ml and 0.5-2mg/ml. The most effective plant extract was Plectranthus barbatus at mic5o and micgo concentration of 0.5 -lmg for all categories of bacterial isolates. It is concluded that selected plant extracts had significant effects on both gram negative and gram-positive bacteria and that carefully guided extraction and characterization of these plant compounds may yield useful antibiotic compounds.