Evaluation of the Antimicrobial Properties of Olive Oil Extract on Selected Pathogenic Bacteria (Staphylococcus haemolyticus and Klebsiella pneumoniae).

Abstract

Background: Olive (Olea europaea L.) products, including fruit, oil, and leaves, are rich in bioactive phenolic compounds with diverse biological activities. Olive leaf extract has gained attention as a natural antimicrobial and antioxidant agent, with reported benefits for cardiovascular and immune health. Key constituents such as oleuropein and hydroxytyrosol exhibit inhibitory effects against pathogens including Staphylococcus haemolyticus and Klebsiella pneumoniae. These findings highlight the therapeutic potential of olive-derived phytochemicals in combating antimicrobial resistance.

Aim: The present study aimed to evaluate the antibacterial activity of olive leaf extract against two pathogenic bacteria: Staphylococcus haemolyticus and Klebsiella pneumoniae.

Materials and Methods: The antibacterial potential of olive leaf extract was assessed using the agar well diffusion method. Ciprofloxacin and co‑trimoxazole served as standard reference antibiotics. Zones of inhibition were measured in millimeters (mm) at different extract concentrations (15, 25, 30, and 60 mg/ml).

Results: For Klebsiella pneumoniae, the olive leaf extract produced inhibition zones of 0, 14 ± 0.4, 15.1 ± 0.6, and 17 ± 0.8 mm at concentrations of 15, 25, 30, and 60 mg/ml, respectively. For Staphylococcus haemolyticus, the inhibition zones were 11.6 ± 1.10, 14 ± 0.75, 15 ± 0.8, and 15.5 ± 1.29 mm at the same concentrations. Notably, the 60 mg/ml formulation demonstrated the highest antibacterial activity against Klebsiella pneumoniae (17 mm), which was comparable to the standard co‑trimoxazole (16 mm).

Conclusion: Olive leaf extract exhibits significant antibacterial activity against both Staphylococcus haemolyticus and Klebsiella pneumoniae. The strongest effect was observed at 60 mg/ml, suggesting its potential as a natural antimicrobial agent comparable to conventional antibiotics.