Methods: Antimicrobial effect was evaluated by measuring adenosine tri-phosphate (ATP) and adenosine mono-phosphate (AMP). ATP is a chemical substance that acts as an energy source for all living organisms on the planet. AMP is derived from ATP during the processing. The presence of ATP or AMP can be considered proof of the presence of a living organism. ATP + AMP were measured at cutting boards, overflows in the bathroom, and necks of yukata (Japanese night clothes), which had been used for nursing skill practice several times by nursing students. The tested area were wiped using the swab stick, which combines a reagent and self-contained swab device (LuciPac Pen, Kikkoman Co. Ltd. Tokyo), after which light is emitted as a result of chemical reaction between luciferase-luciferin-PPDK reagent and ATP and/or AMP. The level of luminescence was measured using the measuring instrument (Lumitester PD-20, Kikkoman, Tokyo), and the degree of cleanliness is determined based on the amount of ATP + AMP detected by it.
Water-soluble essential oils, tea-tree (Melaleuca alternifolla) and eucalyptus (Eucalyptus globulus) dissolved with an emulsifier were used in this study (Biken Co. Ltd. Tokyo). These water-soluble essential oils were diluted to100 times with sterilized distilled water and used as spray. The liquid containing only emulsifier without essential oil was also diluted 100 times and used as a control (control). Samples were obtained by wiping up the surface of the sprayed sites to be tested as mentioned above using the swab stick at 30 minutes after the liquid with essential oil or without (control) was sprayed. A swab stick was moved up and down 10 times in a fixed sized area (4 cm x 4 cm) to wipe up. The site for spraying control liquid was about 5 cm apart from that for essential oils. The significance of difference between essential oil and control was evaluated by applying the Wilcoxon rank sum test and were considered statistical at p<0.05.
Results: ATP + AMP in the necks of yukata showed 867 ± 1635.5 RLU (Relative Light Unit, n=20) for control, and 242.6 ± 381.1 RLU for tea-tree (n=20). For eucalyptus, ATP + AMP showed 163.1 ± 136.3 RLU (n=14) and 333.9 ± 199.6 RLU (n=14) for control. ATP + AMP for tea-tree or eucalyptus showed significant decreases to 39.0 + 29.8 % or 49.2 + 15.6% compared with that for control (100%) in the necks of yukata, respectively. After spraying tea-tree, ATP + AMP significantly decreased to 36.5 + 23.5 % in cutting boards (n=7) and 37.6 + 23.8 % in overflows in the bathroom (n=10).
Conclusion: The spraying the liquid containing essential oils decreased ATP + AMP in the neck of yukata, the cutting board and the overflow in the bathroom in this study. These results indicate that essential oil must be available to prevent infection by spraying liquid containing essential oil to various things in daily life. In order to apply to nursing practice, further investigation about the antimicrobial effects of essential oils would be needed in clinical practice including nursing clothes, linen goods, and so on.