ANTIBACTERIAL ACTIVITY OF TERMINALIA AVICENNIOIDES BARK EXTRACTS AGAINST CLINICAL ISOLATES OF ANTIBIOTIC-RESISTANT KLEBSIELLA PNEUMONIAE

ABSTRACT The increasing prevalence of antibiotic-resistant Klebsiella pneumoniae infections poses a major public health challenge. This study evaluated the antibacterial activity of ethanolic bark extracts of Terminalia avicennioides against clinical isolates of antibiotic-resistant Klebsiella pneumoniae in Lafia, Nasarawa State, Nigeria. Mature bark samples were collected, authenticated, air-dried, and extracted using absolute ethanol. Clinical isolates were obtained from urine, sputum, and wound swabs, identified through colonial morphology, Gram staining, and biochemical tests, and confirmed for drug resistance via disk diffusion. Phytochemical screening revealed high levels of saponins and alkaloids, moderate levels of tannins and flavonoids, slight amounts of carbohydrates, reducing sugars, and cardiac glycosides, and the absence of oxalates. Quantitative analysis showed alkaloids (0.13 ± 0.08 g) as the most abundant, followed by saponins (0.10 ± 0.01g), flavonoids (0.09 ± 0.01g), and tannins (0.07 ± 0.03). Antibacterial activity was determined using the agar-well diffusion method at extract concentrations of 12.5, 25, 50, 75, and 100 mg mL-1. The extract exhibited significant and concentration dependent inhibition (p < 0.05), with zones of inhibition ranging from 0.00 ± 0.00 mm at 12.5 mg mL-1 to 14.17 ± 0.32 mm at 100 mg mL-1, compared to ciprofloxacin (15.10 ± 0.36 mm) at 5µg. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), were 25 mg mL-1 and 50 mg mL-1, respectively. These findings demonstrates that Terminalia avicennioides bark extract possesses potent antibacterial activity against Klebsiella pneumoniae, supporting its traditional use and highlighting its potential as a natural antimicrobial agent for managing antibiotic-resistant Klebsiella pneumoniae infections.