Antibacterial activity of Libyan Juniperus phoenicea L. leaves extracts against common nosocomial pathogens

In ancient times, botanical extracts were essential complementary method for microbial control. This study has been carried out to assess the antibacterial activities of methanol, acetone, and aqueous leaf extracts of Libyan Juniperus phoenicea L. against multidrug-resistant (MDR) clinical isolates (Staphylococcus aureus, S. haemolyticus, Pseudomonas aeruginosa, and Proteus mirabilis) using the agar well diffusion method. Based on the inhibition zone's diameter or appearance, the tested MDR bacteria were identified as susceptible, intermediate, or resistant using the standard criteria. The current study's findings showed that the concentration, type of solvent and bacterial species had a significant impact on the effectiveness of the plant extracts. Results of the study revealed that the methanol and acetone extracts demonstrated moderate to excellent antibacterial properties against all tested bacteria at all predefined concentrations (25, 50, 75, and 100%), with the zone of inhibition ranging from 15.66 to 27.66 mm. Among the tested solvents, the aqueous extract of J. phoenicea was the least effective against the clinical bacterial isolates. Further, the plant's leaf extracts were more effective against Gram-positive bacteria than Gram-negative bacterial pathogens. Most importantly, neither the aqueous extract nor the standard antibiotics inhibited P. aeruginosa, while the methanol and acetone extracts displayed remarkable inhibition zones against all tested bacteria. Consequently, the plant extracts (acetone and methanol) in this study may provide insightful information about the potential use of J. phoenicea leaves as a natural antibacterial agent, which could be used to combat antibiotic-resistant bacteria.