ANTIBACTERIAL ACTIVITY OF AQUEOUS AND N-HEXANE VERNONIA AMYGDALINA LEAVES EXTRACTS AGAINST SELECTED MULTIDRUG RESISTANT ESKAPE PATHOGENS

The rise of multidrug-resistant (MDR) pathogens, particularly within members of the ESKAPE group (Enterobacter sp., Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecium), presents a critical challenge to public health. These pathogens are responsible for severe infections that are increasingly difficult to treat due to their resistance to conventional antibiotics. The increasing prevalence of antibiotic resistance among ESKAPE pathogens necessitates urgent research into alternative therapeutic options. The diminishing effectiveness of traditional antibiotics, which leads to higher rates of morbidity and mortality associated with bacterial infections calls for resorting to natural products, particularly plant extracts, in search of promising alternatives for developing new antimicrobial agents. Vernonia amygdalina, a plant used in traditional medicine, has demonstrated potential antibacterial properties. Evaluating its efficacy against MDR ESKAPE pathogens could provide insights into its application as a natural antimicrobial agent especially in the study area. This study aimed to compare the yield and phytochemical composition (using both conventional and Fourier-transform infrared (FT-IR) spectroscopy assays) of aqueous and n-hexane extracts of Vernonia amygdalina, as well as determine the antibiogram and multidrug resistance profiles of selected ESKAPE pathogens from UMYU Microbiology Laboratory, and finally compare the antibacterial activity of the extracts against the pathogens. The fresh leaves of Vernonia amygdalina were extracted using aqueous and n-hexane solvents, and the yield of each extract was calculated. Phytochemical screening was performed to identify bioactive compounds using conventional tests, and FT-IR spectroscopy was utilized to analyze the functional groups present in the extracts. The antibacterial activity was assessed using the agar well diffusion method, measuring zones of inhibition against clinical isolates of ESKAPE pathogens. Statistical analyses (two-way ANOVA and Welch test), were conducted to evaluate the significance of the results. The results indicated that n-hexane extract yielded significantly more (28.81%) than the aqueous extract (9.87%) (Welch test: p < 0.0001). The phytochemical analysis revealed the presence of cardiac glycosides, saponins, steroids and flavonoids. FT-IR analysis identified bioactive compounds such as terpenoids, polyacetylenes, cyanogenic glycosides, and fatty acid nitriles in the aqueous extract, while the n-hexane extract contained terpenoids, steroids, triglycerides, and lipophilic alkaloids. The antibacterial activity results showed that both extracts exhibited similar inhibition zones compared to the positive control (p = 0.066). Conclusively, this study demonstrated that both aqueous and n-hexane extracts of V. amygdalina possess significant antibacterial activity against MDR ESKAPE pathogens, with the n-hexane extract showing higher yields and a broader range of bioactive compounds. These findings support the potential of V. amygdalina as a source of novel antimicrobial agents. The study recommends that future research should focus on quantifying the specific bioactive compounds using GC-MS analysis, exploring other extraction methods to maximize yield, and evaluating the toxicity profile of the extracts before considering them for drug development.