Comparative Antibacterial Activity of Three Medicinal Plants and Antibiotic Sensitivity of Klebsiella Pneumoniae Clinical Isolates

Abstract

Background: The increasing prevalence of infectious diseases has renewed interest in herbal extracts as complementary therapeutic agents, due to their bioactive compounds.

Objectives: This study evaluated the antibacterial potential of three medicinal plants against clinical isolates of multidrug-resistant (MDR) Klebsiella pneumoniae.

Materials and Methods: Ethanol leaf extracts of Allophylus spicatus Radlk. (Sapindaceae), Carica papaya L. (Caricaeae) and Macrosphyra longistyla (DC.) Hook. F. ex Hiern (Rubiaceae) were assessed for antibacterial activity against clinical isolates of MDR Klebsiella pneumoniae using agar well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Antibiotic susceptibility testing was performed using a multidisc antibiotic ring as a positive control. Total phenol (TPC), flavonoid (TFC), and phytosterol (TSC) contents of the extracts were also determined.

Results: Among the extracts tested, only A. spicatus leaf extract exhibited antibacterial activity against MDR K. pneumoniae, producing inhibition zones ranging from 11.67 ± 0.33 to 20.33 ± 0.33 mm against five of the ten isolates. Both MIC and MBC were valued 25.6 mg/mL for two of the susceptible strains. Nitrofurantoin consistently inhibited all tested isolates. Extract of A. spicatus showed the highest TPC (192.187 ± 1.139 mg GAE/g extract) compared with the other extracts.

Conclusions: Allophylus spicatus leaf extract demonstrates antibacterial activity against clinical isolates of MDR Klebsiella pneumoniae, likely attributable to its high phenol content, indicating its potential as a source of antibacterial agents.