Efficacy of Melaleuca alternifolia and Pelargonium graveolens Oils Against Staphylococcus aureus and Staphylococcus epidermidis: An In Vitro Study

The rise of antibiotic-resistant bacteria around knee implants significantly diminishes patients' quality of life and mobility, necessitating innovative solutions to combat infections. This study explores the antimicrobial efficacy of tea tree (<i>Melaleuca alternifolia</i>) and geranium (<i>Pelargonium graveolens</i>) essential oils against <i>Staphylococcus aureus</i> and <i>Staphylococcus epidermidis</i>. Utilizing bioassay preparation methods and minimal inhibitory concentration (MIC) assays, we found that tea tree oil notably inhibited <i>S. aureus</i> growth, while Geranium oil effectively targeted <i>S. epidermidis</i>. Scanning and transmission electron microscopy revealed substantial morphological alterations in both bacterial strains following treatment with the essential oils. Twenty compounds were identified by GC/MS chemical profiling in tea tree oil, with α-pinene (21.6%), γ-terpinene (21.1%), and terpinen-4-ol (17.3%) being the main ingredients. Forty compounds were found in Geranium oil, with citronellol (42.2%), geraniol (30.5%), and linalool (9.8%) constituting the majority. Our findings suggest that incorporating these essential oils into orthopaedic implants could significantly enhance their antibacterial effectiveness, offering a promising alternative to traditional antibiotic treatments and potentially reducing infection rates associated with knee implants. This research not only contributes to the understanding of natural antimicrobial agents but also paves the way for their practical application in clinical settings, addressing the critical challenge of antibiotic resistance.