Objective: This study aimed to determine the antimicrobial property of oregano (Plectranthus amboinicus) crude leaf extract against pathogens that infect the throat, specifically Streptococcus pyogenes and Candida albicans using the broth and checkerboard dilution methods.

Methods: This study employed an experimental study design using broth dilution method for the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) against Streptococcus pyogenes ATCC 19615, and minimum fungicidal concentration (MFC) against Candida albicans ATCC 14053 of P. amboinicus crude extract (PA extract). Checkerboard dilution method was then used for determination of the synergy between PA extract and the standard antimicrobials.

Results: In vitro growth inhibition of S. pyogenes (MIC 0.13 g/mL) and C. albicans (MIC 0.03 g/mL) was exhibited by the PA extract. The highest concentration of PA extract used in this study was not sufficient to demonstrate bactericidal and fungicidal activity (MBC >0.25 g/mL, MFC >0.25 g/mL). Results of checkerboard dilution method revealed that PA extract when combined with either penicillin (for S. pyogenes) or nystatin (for C. albicans) demonstrated indifference.

Conclusion: The crude extract of Plectranthus amboinicus has the capability to inhibit the growth of both S. pyogenes and C. albicans. This demonstrates its potential use in the treatment of throat infections caused by these organisms.

Key Words: Plectranthus amboinicus, oregano, antimicrobial, throat infections, herbal medicine