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Antimicrobial Activity of Mandelic Acid Against Methicillin-Resistant Staphylococcus aureus: a Novel Finding with Important Practical Implications

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Background: Staphylococcus aureus is a major health concern worldwide especially in cutaneous diseases. The aim of this study was to determine the in vitro antimicrobial activity of mandelic acid against Staphylococcus aureus isolates. Methods: In this study, the susceptibility of mandelic acid against two type strains and nineteen clinical isolates of Staphylococcus aureus was assessed in vitro. Results: Mandelic acid in different concentrations of 40, 80 and 160 mg/ml showed in vitro antibacterial activity against all tested clinical isolates of Methicillin-resistant Staphylococcus aureus (MRSA) as well as the tested type strains in disk diffusion method with inhibitory zones of 11-20 mm. The minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC) for methicillin-sensitive staphylococcus aureus (MSSA) and MRSA type strains were 20/20 and 40/40 mg/ml respectively. For the nineteen clinical MRSA isolates, MIC50 and MIC90 were 20 and 40 (mg/ml) respectively and MBC50 and MBC90 were 20 and 80 (mg/ml) respectively. Conclusion: Our results suggest that mandelic acid has an antibacterial activity against MRSA and might be a useful addition to anti-MRSA armamentarium. Further investigations regarding the use of mandelic acid in a suitable moisturizer for atopic skin, to exert the dual effects of lubrication and MRSA eradication is recommended.
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