Application of orange essential oil as an antistaphylococcal agent in a dressing model.
BACKGROUND
Staphylococcus aureus is the pathogen most often and prevalently involved in skin and soft tissue infections. In recent decades outbreaks of methicillin-resistant S. aureus (MRSA) have created major problems for skin therapy, and burn and wound care units. Topical antimicrobials are most important component of wound infection therapy. Alternative therapies are being sought for treatment of MRSA and one area of interest is the use of essential oils. With the increasing interest in the use and application of natural products, we screened the potential application of terpeneless cold pressed Valencia orange oil (CPV) for topical therapy against MRSA using an in vitro dressing model and skin keratinocyte cell culture model.


METHODS
The inhibitory effect of CPV was determined by disc diffusion vapor assay for MRSA and vancomycin intermediate-resistant S. aureus (VISA) strains. Antistaphylococcal effect of CPV in an in vitro dressing model was tested on S. aureus inoculated tryptic soya agar plate. Bactericidal effect of CPV on MRSA and VISA infected keratinocyte cells was examined by enumeration of extra- and intra-cellular bacterial cells at different treatment time points. Cytotoxic effects on human skin cells was tested by adding CPV to the keratinocyte (HEK001) cells grown in serum free KSFM media, and observed by phase-contrast microscope.


RESULTS
CPV vapour effectively inhibited the MRSA and VISA strains in both disc diffusion vapour assay and in vitro dressing model. Compared to untreated control addition of 0.1% CPV to MRSA infected keratinocyte decreased the viable MRSA cells by 2 log CFU/mL in 1 h and in VISA strain 3 log CFU/mL reduction was observed in 1 h. After 3 h viable S. aureus cells were not detected in the 0.2% CPV treatment. Bactericidal concentration of CPV did not show any cytotoxic effect on the human skin keratinocyte cells in vitro.


CONCLUSIONS
At lower concentration addition of CPV to keratinocytes infected with MRSA and VISA rapidly killed the bacterial cells without causing any toxic effect to the keratinocytes. Therefore, the results of this study warrant further in vivo study to evaluate the potential of CPV as a topical antistaphylococcal agent.
Center for Food Safety and Department of Food Science, University of Arkansas, Fayetteville, AR 72701, USA.
Arunachalam
A
Muthaiyan
Debabrata
D
Biswas
Philip G
PG
Crandall
Brian J
BJ
Wilkinson
Steven C
SC
Ricke
D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002056:Burns / Q000188:drug therapy / Q000382:microbiology; D018929:Cell Culture Techniques; D032084:Citrus sinensis / Q000737:chemistry*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000382:microbiology; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D010938:Plant Oils / Q000494:pharmacology / Q000627:therapeutic use*; D012867:Skin / Q000166:cytology / Q000187:drug effects* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D020713:Vancomycin Resistance; D014945:Wound Healing / Q000187:drug effects*; D014946:Wound Infection / Q000188:drug therapy / Q000382:microbiology
D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D010938:Plant Oils; C087245:orange oil