Abstract
Background: S. aureus is a multidrug-resistant (MDR) bacterium that poses a significant public health threat globally. In response, plants have emerged as promising alternatives in combatting infections caused by this pathogen. This study aims to evaluate the efficacy of two medicinal plants against MDR Gram-positive Staphylococcus aureus.
Methods: The antibacterial activity of various plant extracts was assessed both individually and in combination with conventional antibiotics using the microdilution assay. Additionally, qualitative phytochemical screening was conducted following established experimental protocols.
Results: The extracts from the evaluated plants demonstrated antibacterial properties, with Minimum Inhibitory Concentrations (MICs) ranging from 32 to 1024 µg/mL. The methanolic extract from the leaves of Terminalia laxiflora exhibited strong activity against the S. aureus ATCC 25923 strain, achieving a MIC of 32 µg/mL. Likewise, the extract from the fruits of Azadirachta indica showed excellent activity against both the S. aureus MRSA A9 isolate and the ATCC 25923 strain, also with a MIC of 32 µg/mL. The different extracts, at concentrations of MIC/2 and MIC/4, demonstrated an antibiotic-enhancing effect, with Activity Enhancement Factors (AEF) ranging from 2 to 128. Extracts from the leaves of T. laxiflora and the fruits of A. indica enhanced the effectiveness of antibiotics against at least 62.5% of the tested isolates. The antibiotics that exhibited improved efficacy included cefixime, ceftriaxone, ciprofloxacin, doxycycline, levofloxacin, penicillin, and tetracycline. Qualitative phytochemical screening revealed the presence of alkaloids, phenols, and flavonoids in the leaves of T. laxiflora, while phenols and flavonoids were identified in the fruits of A. indica.
Conclusion: Extracts from T. laxiflora and A. indica contain antibacterial compounds that hold potential for addressing infections caused by MDR S. aureus.
Keywords: Antibacterial; Terminalia laxiflora; multidrug resistance; Azadirachta indica.
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