Sunday, September 8, 2013

Some Essential Oils Inhibit MRSA, Influenza, & Strep - Scientific Studies

essential oils photo: Essential oils essential-oil.jpg

Photo Credit: Photobucket

My workplace strives to become Louisville's first green pre-school. Since this is right up my alley our director has invited me to do some of the legwork.

My first project was to register us with Terracycle, a non-profit organization that turns typically discarded packaging, like salty snack bags and energy bar wrappers, into stuff that does not get thrown away, like picnic tables and park benches. And, since preschools are perpetual germ factories now I'm researching the anti-microbial properties of essential oils (for diffusion). Next I will raise funds for a steam vacuum so the babies don't have to crawl on floors cleaned with harsh chemicals.

I've learned that some essential oils have actually been studied for their anti-bacterial and anti-viral properties. Here is a sample of the many studies available on Pub Med.

essential oils photo: Lemon_a lemons.jpg


In Vitro Antibacterial Activity of Essential Oils against Streptococcus pyogenes.

This study used a disc infusion method to test the in vitro anti-bacterial aspects of eighteen different essential oils against streptococcus pyogenes, a bacteria that causes strep throat. Fourteen of the oils demonstrated anti-bacterial action against Streptococcus pyogenes. These include, among others: cinnamon, lemongrass, thyme, oregano, and winter savory. This study suggests that these oils might be helpful to patients suffering from bacterial throat infections.

2012 Jan 1;13(1):71-4.
Antimicrobial activity of commercially available essential oils against Streptococcus mutans.

This study tested the in vitro effectiveness of nine essential oils against Streptococcus mutans. Cinnamon oil was most effective against Streptococcus mutans followed by lemongrass oil, cedarwood oil, clove oil, and eucalyptus oil. Wintergreen oil, lime oil, peppermint oil and spearmint oil had no antibacterial effectiveness. The authors suggest the useful oils as a possible alternative to other antibacterial agents for treating oral infections.

 J. Antimicrob. Chemother. 47 (5): 565-573.                                    
Antibacterial activity of essential oils and their major constituents against respiratory tract pathogens by gaseous contact

The anti-bacterial effectiveness of fourteen essential oils in their vaporized states was examined against Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. All of the oils showed activity, but cinammon, lemongrass, and thyme (wild and red) were the most impressive, suppressing all of these and e coli too (except lemongrass), which was used as a control. They hyper-link above leads to the complete study.  

2012 Jun 28;12:81.l
Chemical composition of 8 eucalyptus species' essential oils and the evaluation of their antibacterial, antifungal and antiviral activities.
Studied the anti-bacterial, anti-fungal, and antiviral activities in eight eucalyptus species. E. bicostata had the best anti-viral activity. " E. odorata showed the strongest activity against S. aureus, H. influenzae, S. agalactiae, S. pyogenes, S. pneumoniae and against all the tested fungal strains."

Antimicrobial Activity of Essential Oils against Streptococcus mutans and their Antiproliferative Effects
"EO showed activity at low concentrations, and their selected active fractions were also effective against biofilm formed by S. mutans and human tumor cell lines." This abstract does not say which oils were tested.

2011 Nov-Dec;76(9):H226-30
Essential oil of Curcuma longa inhibits Streptococcus mutans biofilm formation.
Found turmeric oil inhibits carcinogenic properties of strep mutans.

2011 Nov 21;16(11):9651-64
Biological activity of carbazole alkaloids and essential oil of Murraya koenigii against antibiotic resistant microbes and cancer cell lines.
Found curry oil inhibits anti-biotic resistant strains of  Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumonia. Also found that the oil exhibits anti-tumor properties against certain cell lines.

flu photo: The Flu Flu.jpg


2012 Jan 31;139(2):668-71
Chemical compositions and anti-influenza activities of essential oils from Mosla dianthera.

Mosla Dianthera oil reduced lung titers in influenza infected mice. It also inhibited pneumonia, reduced levels of serum IFN-γ and IL-4, and enhanced antioxidant activity in the lung tissue of the infected mice.

2011 Jan;89(1):83-8
Activity of Melaleuca alternifolia (tea tree) oil on Influenza virus A/PR/8: study on the mechanism of action.

Found tea tree oil effective at inhibiting influenza H1N1 in MDCK cells within the first two hours of exposure to the virus. This suggests that exposure to the oil inhibits an early step replication process of the virus. Exposure to the oil during later stages of infection had no effect.

2010 Nov 15;10:69
Protective essential oil attenuates influenza virus infection: an in vitro study in MDCK cells.

Found that the commercially available essential oil blend On Guard suppressed influenza virus PR8 in MDCK cells in a dose dependent manner. Abstract goes into exactly how and why.

2009 Dec;49(6):806-8
In vitro antiviral activity of Melaleuca alternifolia (Tea Tree) essential oil.

Tea tree oil shows antiviral activity against influenza A/PR/8 virus subtype H1N1.

hospital photo: hospital hospital.png


2009 Apr;48(4):387-92.
***Vapour-phase activities of essential oils against antibiotic sensitive and resistant bacteria including MRSA***
Diffused a mix of geranium and Lemongrass called BioScent in a ST Pro Machine. The oils were tested against antibiotic resistant and antibiotic sensitive strains like MRSA. They not only inhibited the growth of these bacteria, but reduced surface and airborne levels. However, results varied depending on method (89% & 39%). The authors conclude that BioScent may be useful as an air disinfectant.

2005 Mar;10(3):123-6
Is tea tree oil effective at eradicating MRSA colonization? A review.

This is a review of other studies on the topic. It concludes that tea tree would not be useful against MRSA.

2009 Oct;37(7):392-7.
The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections.
Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit,Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil were tested against staph. Thyme white, Lemon, Lemongrass and Cinnamon oil were most effective, but the other oils also demonstrated efficacy. The authors conclude that essential oils represent inexpensive and effective topical treatments for resistant MRSA and candida strains.

2012 Nov;113(5):1217-27.
The anti-biofilm activity of lemongrass (Cymbopogon flexuosus) and grapefruit (Citrus paradisi) essential oils against five strains of Staphylococcus aureus
Used disc diffusion method. Tested lemongrass, grapefruit, bergamot and lime against staph. Found  lemongrass had the most antimicrobial and anti-biofilm activity.

2012 May;112(5):1020-33.
Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus.

2011 Dec;17(6):399-402.
Antibacterial activities of essential oils from eight Greek aromatic plants against clinical isolates of Staphylococcus aureus.

The abstract does not say which oils were tested, only that they were from Greece. It does say that the oils tested showed not efficacy against staph.

2009 Nov;75(21):6850-5.
Effect of cinnamon oil on icaA expression and biofilm formation by Staphylococcus epidermidis.

Found cinnamon oil is an effective antimicrobial agent against staph biofilms on surfaces.



I'm not sure how to apply these results in the real world. Most of these studies were conducted in vitro, but would those results hold up outside a test tube?  The few studies that diffused oils into the air suggest that they might. But they used industrial style diffusers. Can I get decent results with inexpensive ones bought online for twenty bucks a piece? Hard to say.

I do know that a growing number of hospitals and nursing homes are diffusing essential oils for various purposes to positive effect, so why not schools?

Hospitals Using Alternative Medicine to Ease Kids' Pain - NBC Washington

Essential Oils 'Combat Super Bug' - BBC News

Vanderbilt Hospital ER Diffuses Essential Oils - Fox News

We are not looking to treat the children for anything, though. We just want to kill big bad germs in the air and on surfaces, like we currently do with Lysol spray or Clorox Wipes. And, if this happens to obliterate the dirty diaper stink too, well hey, that's just an added bonus.


Though essential oils are generally recognized as safe, not all oils are good for all people and some oils have more cautions than others. For instance, Rosemary is contraindicated for pregnancy and epilepsy, but the citrus oils have few cautions. Therefore, I wasn't the least bit surprised when the above Fox News clip said Vanderbilt Hospital ER uses a citrus blend. That would be the safest choice for the greatest number of people. I want to choose the safest oils for my work setting as well.

It is strep and influenza we see most in daycares. It looks like cinnamon and lemongrass are the most effective at inhibiting strep, followed by eucalyptus, thyme, and oregano. Tea tree appears to be the super star against influenza. So, let's take a look at the safety profiles of these oils.

Cinnamon: The manual "Essential Oils Safety", by Robert Tisserland lists several health conditions that should avoid exposure, so that rules out routine diffusion. We could still probably use it in the steam vacuum, though.

Lemongrass: Tisserland says to avoid in children. That's out. Bummer.

Eucalyptus, thyme, and oregano: The only cautions these three carry that could concern children is as a possible skin and mucous membrane irritant (Tisserland), but they would never come in direct contact with the oils.

Tea Tree: No major concerns beyond the usual skin irritation with direct contact (Tisserland).


Eucalyptus and Tea Tree on account of their positive safety profiles and pleasant aromas.

I hope you didn't get too lost among all that research. I know I did.


Related Posts:

Can Vetiver Help ADHD & Autism?

Rosemary Essential Oil Improves Memory: Emerging Scientific Evidence


This post is linked to Frugal Days, Sustainable Ways.

Tags: Essential Oils and flu, Aromatherapy and flu, strep, and MRSA, studies

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