PT - JOURNAL ARTICLE AU - Mariah Ndilimeke Muhongo AU - Mourine Kangogo AU - Christine Bii TI - The Antimicrobial Activity of <em>Pechuel-Loeschea leubnitziae</em> Leaf Extract and its Effect on The Expression Level of Methicillin Resistant <em>Staphylococcus Aureus</em> and <em>Candida albicans</em> Virulence-Associated Genes AID - 10.1101/2022.01.11.475881 DP - 2022 Jan 01 TA - bioRxiv PG - 2022.01.11.475881 4099 - http://biorxiv.org/content/early/2022/01/11/2022.01.11.475881.short 4100 - http://biorxiv.org/content/early/2022/01/11/2022.01.11.475881.full AB - The complete halt in the synthesis of new effective antimicrobial compounds is a global concern. Pathogenic microorganisms’ virulence mechanisms seem to have a significant impact on their pathogenesis. The purpose of this study was to examine the antimicrobial activity of the ethanol and methanol fractions of Pechuel-Loeschea leubnitziae leaf extract, as well as its effect on the expression level of virulence-associated genes.The extract’s fractions were evaluated for antimicrobial activity against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae (clinical), Methicillin-resistant Staphylococcus aureus, and Candida albicans ATCC 90029. The test organism’s antibiogram pattern was determined. The extracts’ attenuation effect on the target genes of the susceptible organisms was investigated employing relative quantification using RT-qPCR. The test organism’s antibiogram pattern revealed that it was drug-resistant, intermediate, and sensitive. The extracts tested positive for antimicrobial activity against Methicillin-resistant Staphylococcus aureus and Candida albicans ATCC 90029, with zones of inhibition varying from 20.33 to 29 mm. The lowest recorded MIC value was 4.688 mg/ml, while the highest was 37.5 mg/ml. In contrast to the methanol extract, the ethanol extract had a cidal action at a lower dose. The ethanol extract’s Sub-MIC (18.25 mg/ml) merely reduced the expression of the hly gene in MRSA. The MRSA virulence genes were not suppressed by the sub-MIC of methanol extract (18.25 mg/ml). Notably, the expression of als1, pbl1, and sap1 in Candida albicans ATCC 90029 was significantly attenuated when exposed to sub-MICs of ethanol extract (2,344 mg/ml) and methanol extract (9.375 mg/ml). Per the findings of this research, the leaves of P. leubnitziae could be a source of an effective antimicrobial agent in the therapy of MRSA/Candida-related disorders.Competing Interest StatementThe authors have declared no competing interest.