Reduction of surface contamination and biofilms of Enterococcus sp. and Staphylococcus aureus using a citrus-based vapour

Background: Antibiotic-resistant organisms such as meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus sp. (VRE) are an ongoing problem in hospitals. Essential oil vapours (EOs) have been shown to reduce environmental bacterial contamination.

Aims: To assess the efficacy of Citri-V™, a vaporized blend of citrus EOs (orange: bergamot, 1:1 v/v) (Belmay, Northampton, UK), at removing Enterococcus sp. and S. aureus from stainless steel surfaces; and to investigate its effect on the formation of bacterial biofilms.

Methods: A microplate assay was used to assess the effect of the citrus vapour on the formation of biofilms and their metabolic activity. Biofilm removal from stainless steel surfaces was measured by a colorimetric assay and by digital microscopy.

Findings: The citrus vapour reduced VRE and MRSA on stainless steel surfaces by 1.5-3log(10) after 24h exposure. Staphylococcal biofilms were reduced both during and after formation, whereas enterococcal biofilms were significantly reduced (P≤0.05) only after formation. Metabolic activity decreased by up to 72% in strains tested. Two-dimensional digital microscopy showed reductions in biofilm coverage of the stainless steel disc by as much as 99.5%.

Conclusion: Citrus vapour has potential for application in the clinical environment, for instance as a secondary disinfectant to reduce surface contamination by VRE and MRSA.