Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans, Staphylococcus aureus, and Candida spp.

Abstract

BACKGROUND: The oral cavity harbors more than 700 species of bacteria, which play crucial roles in the development of various oral diseases including caries, endodontic infection, periodontal infection, and diverse oral diseases. AIM: To investigate the antimicrobial action of <i>Cymbopogon Schoenanthus</i> and <i>Pelargonium graveolens</i> essential oils against <i>Streptococcus mutans, Staphylococcus aureus, Candida albicans, Ca. dubliniensis</i>, and <i>Ca. krusei</i>. METHODS: Minimum microbicidal concentration was determined following Clinical and Laboratory Standards Institute documents. The synergistic antimicrobial activity was evaluated using the Broth microdilution checkerboard method, and the antibiofilm activity was evaluated with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. Data were analyzed by one-way analysis of variance followed by the Tukey post-hoc test (<i>P</i> ≤ 0.05). RESULTS: <i>C. schoenanthus</i> and <i>P. graveolens</i> essential oils were as effective as 0.12% chlorhexidine against <i>S. mutans</i> and <i>St. aureus</i> monotypic biofilms after 24 h. After 24 h <i>P. graveolens</i> essential oil at 0.25% was more effective than the nystatin group, and <i>C. schoenanthus</i> essential oil at 0.25% was as effective as the nystatin group. CONCLUSION: <i>C. schoenanthus</i> and <i>P. graveolens</i> essential oils are effective against <i>S. mutans, St. aureus, Ca. albicans, Ca. dubliniensis</i>, and <i>Ca. krusei</i> at different concentrations after 5 min and 24 h.