Browsing by Author "Iikasha, Albertina M."
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Item Antimicrobial and antiplasmodial activity displayed by actinomycetes isolated from soils from Kavango and Hardap regions in Namibia(2018) Iikasha, Albertina M.; Dushimemaria, Florence; Mbewe, Maria; Eiman, H.; Mumbengegwi, Davis R.Plasmodium falciparum and multidrug resistant bacteria such as Mycobacterium avium, Staphylococcus aureus and Escherichia coli are among the top causes of morbidity and mortality especially in developing countries. These pathogens are responsible for the reported antibiotic resistance incidents globally. Due to the increase in antibiotic resistance worldwide, there is an urgent need for new bioactive compounds. This study aimed at determining the antiplasmodial and antimicrobial activity of secondary metabolites produced by soil actinomycetes. Soil samples were collected from Kavango and Hardap regions and cultured on various media to isolate and identify actinomycetes. Secondary metabolites produced were extracted using different solvents. The antimicrobial activity of different isolated secondary metabolites was determined against M. avium, S. aureus and E. coli. Antiplasmodial activity of four bioactive fractions with potent antibacterial activity was further determined against a chloroquine resistant (D10) P. falciparum strain at various concentrations. Bioactive compounds from two isolates displayed activity against M. avium, whilst another two showed activity against E. coli. None of the secondary metabolites displayed activity against S. aureus. A concentration dependent reduction in parasitaemia for P. falciparum was observed across all four fractions both after 24 and 48 h. These results display a vast potential antibacterial and antiplasmodial activity and should be considered for future drug development.Item Evaluation of antibactrial activity of medicinal plant extracts against clinic isolates of pathogens from children with acute gastroenteritis at Katutura State Hospital Windhoek, Namibia(African Journal of Traditional, Complementary and Alternative Medicines, 2019) Iikasha, Albertina M.Background: Diarrhea is a major health concern in Namibia with an estimate of 17000 cases in 2015 in Omusati and Kunene regions. The present study aimed at isolating and identifying gastrointestinal bacteria from stool samples of children admitted at Katutura hospital, Windhoek, and to determine the efficacy of selected medicinal plants used in treating gastroenteritis in Namibia. Materials and Methods: Stool samples were collected for 6 months from children under age five admitted with acute diarrhea. Seeplex12 automated DNA extractor and PCR were used for isolation and identification of bacterial DNA from the samples. Serially diluted stool samples were cultured on selective media, sub-cultured in Nutrient broth and preserved in 80% glycerol. Parts of Boscia albitrunca, Ziziphus mucronata, Combretum apiculatum, Solanum linnaeanum and Terminalia sericea were collected, dried, ground, and extracted using distilled water and ethanol. Disc diffusion method was used to determine the antibacterial activity of the plant extracts against isolated bacteria. Results: A total of 12 out of the 18 stool samples collected had bacterial pathogens successfully identified by PCR. 33.3% were positive for Salmonella, 11.1% for E. coli 157:H7 VTEC and 22.2% for E.coli H7. C. apiculatum organic extracts exhibited potent antibacterial activity of (16± 0.57mm) at 1000 µg/ml against Shigella and Salmonella with a moderate minimum inhibitory concentration (MIC) of 250 µg/ml against Salmonella. Salmonella and Shigella showed resistance to 10 µg/ml of ampicillin. Conclusion: Plant extracts showed in vitro antibacterial activity. However, toxicology and in vivo efficacy of these plant extracts should be determined before recommending their mainstream uses.Item An investigation into the antibacterial activity of pigmented secondary metabolites isolated from streptomyces from Windhoek soil(University of Namibia, 2017) Iikasha, Albertina M.; Eiman, H.; Mumbengegwi, Davis R.There is an increase in mortality from infectious diseases due to an increase in antibiotic resistance worldwide. Hence, his study aimed at investigating the antibacterial activity of Streptomyces that produces pigmented secondary metabolites .The soil samples were collected from 3 different sites in Windhoek. Streptomyces were isolated on starch case in agar. Biochemical and physiological tests were used to identify Streptomyces species. Case in slantagar method was used for preliminary anti-bacterial test. Chloroform and n-Hexane were used to extract secondary metabolites by solvent-liquid extraction method.Thin layer chromatography plates were used for antibacterial activity of the isolated secondary tabolites.Minimum inhibitory concentration of isolated secondary metabolites was determined by the broth dilution method at concentrations ranging from 50to1.5 μg/ml. Six out of nine Streptomyces isolates showed antibacterial activity against at least one of three test bacteria. Streptomyces isolate 1exhibited potentactivityof19.5mm ± 0.056 against M. avium. Different pigmented secondary metabolites were produced and showed antibacterial activity against at least against one of three test organism. Streptomyces isolate 4 and 6 showed the lowest minimum inhibitory concentration of 6.25 μg/ml against M. avium and E. faecialis. The results showed that Windhoek soil contain antibiotic producing Streptomyces.Item Phytochemical screening and antibacterial testing of selected Namibian medicinal plants against laboratory and clinical bacteria that cause Diarrhoea(University of Namibia, 2016) Iikasha, Albertina M.Medicinal plants are rich in a wide variety of bioactive compounds associated with various ailments; including antibacterial activity and some of them have been used worldwide in traditional settings to treat diarrheal diseases. However evidence on safety and efficacy of some of these traditional medicinal plants is lacking, preventing their mainstream use. This study aimed at determining the antibacterial activity of Boscia albitrunca, Ziziphus mucronata, Combretum apiculatum, Solanum linnaeanum and Terminalia sericea against clinical and laboratory diarrheal pathogens and screen selected plants for the presence of major phytochemical compound. Plant parts (bark, roots and twig) were collected from Kunene region and extracted using aqueous and organic solvents and screened for the presence of triterpenoids, saponins, flavonoids, steroids, coumarins, tannins and alkaloids by thin layer chromatography (TLC). Antibacterial activities of the organic and aqueous extracts were determined against laboratory strains of Escherichia coli, Shigella bodyii, Staphylococcus aureus and Listeria monocytogenes and clinical strains of Salmonella, E. coli and Shigella, by disc diffusion method at three different concentrations (250, 500 and 1000 μg/ml). The average inhibition zones were determined on Mueller- Hinton agar plates. Phytochemical screening revealed higher presence of antibacterial compounds triterpenoids, saponins, flavonoids, steroids, coumarins and alkaloids in organic extracts and tannins in aqueous extracts. The organic extracts of T. sericea showed broad spectrum antibacterial activity against both clinical and laboratory diarrheal pathogens. The highest antibacterial activities at the lowest concentration were observed from organic extracts of S. linnaeanum against laboratory L. monocytogenes (15.5± mm, n=3) and C. apiculatum against clinical Salmonella (12 ± mm, n=3) at 250 μg/ml. In aqueous extracts, C. apiculatum showed stronger antibacterial activity against clinical Shigella (12 ± mm, n=3) and T. sericea against laboratory strains of E. coli and Listeria monocytogenes (9 ± mm, n=3) at 500 μg/ml. Ampicillin showed antibacterial activity against laboratory strains of S. boydii and S. typhi however it showed no antibacterial activities against clinical strains of Shigella and Salmonella. Organic extracts of T. sericea and C. apiculatum also showed a lowest Minimum inhibitory concentration (MIC) of 250 μg/ml against E. coli and Salmonella respectively. Minimum inhibitory concentration of 62.5 μg/ml was recorded for T. sericea and C. apiculatum organic extracts against laboratory strains of S. aureus and E. coli respectively. Organic extracts of T. sericea and C. apiculatum showed an MIC of 250 μg/ml against clinical E. coli and Salmonella respectively. The study confirmed the possibility of using these plant extracts to develop alternative medicine to treat diarrheal pathogens.