Antimicrobial activity of Zornia apiculata and Ipomoea kituiensis against WHO-priority drug-resistant clinical isolates

Background.The rise of antibiotic resistance has become a critical medical concern, prompting the World Health Organization (WHO) to publish a list of priority drug-resistant clinical pathogens. Medicinal plants are considered a potential source for developing novel antimicrobial agents. However, studies on the antimicrobial properties of many such plants remain limited, despite their extensive traditional use. Objective. To evaluate the antimicrobial activity of Zornia apiculata and Ipomoea kituiensis leaf extracts against multidrug-resistant (MDR) bacteria and yeast to support their traditional medicinal use. Methods. An in vitro study assessed the antimicrobial potential of leaf extracts from Z. apiculata and I. kituiensis, sourced from the Omo Valley. Extracts were prepared using selected organic solvents and tested against WHO-prioritized MDR bacterial and fungal isolates. Results. The overall activity indices were 88.3% for Z. apiculata and 83.3% for I. kituiensis. The methanol extract of Z. apiculata showed an activity index of 100%, with inhibition zones of 21.1 ± 1.3–21.8 ± 1.5 mm against Gram-positive and 13.8 ± 1.8–20.8 ± 1.5 mm against Gram-negative bacteria. It also exhibited moderate anti-Candida activity (12.5 ± 0.5 mm). Against MDR isolates, this extract showed inhibition zones of 18.3 ± 1.2–18.5 ± 0.7 mm, with minimum inhibitory concentration (MIC) values of 2.5–10 mg/mL and total antimicrobial activity (TAA) ranging from 9.6–73.8 mL/g. A minimum bactericidal concentration (MBC)/MIC ratio of 0.5 indicated bactericidal action. Both extracts had MIC and MFC values of 5 mg/mL and 10 mg/mL against Candida albicans, respectively (MIC/MFC = 0.5). Conclusion. These findings support the traditional use of Z. apiculata and I. kituiensis for treating infectious diseases in South Omo communities.