Yarrow Oral Presentation by Victoria Roy

Antimicrobial Effects of Yarrow (Achillea millefolium) Essential Oil

Victoria A. RoyKimberly A. Hays, Ph.D.

Department of Natural ScienceDalton State College

Achillea millefolium• Herbaceous, perennial, flowering plant•Native to Asia, Europe and North America•Strong, sweet scent•Flowers May – June •Three color morphs

Yarrow History• Achilles– Soldiers wounds– Scientific name origin

• Native Americans – 46 tribes

• Algonquin• Lenape

– 28 ailments• Kidney disorders• Stomach disorders• Open wounds

• Greece– Military herb

Essential Oils: Growing Popularity

Objective

The objective of our study was to determine the antimicrobial effects of four commercially

purchased yarrow extracts against four common strains of bacteria.

Bacillus cereus

• Gram-positive• Rod shaped• Endospore forming• Pathology– Two types of food poisoning • Enteric and emetic

Escherichia coli

• Gram-negative• Rod-shaped • Found in lower intestine

of homoeothermic organisms• Opportunistic pathogen• Pathology– Food poisoning, urinary tract infections, neonatal

meningitis, Gram-negative pneumonia

Staphylococcus aureus

• Gram-positive • Coccal • Opportunistic pathogen• Found in normal skin flora • Pathology– MRSA– Staphylococcal scalded skin syndrome

• Produces toxins that cause blisters• Ritter’s disease

Pseudomonas aeruginosa

• Gram-negative • Rod-shaped• Opportunistic pathogen– Burn victims– Cystic fibrosis• Adheres to tissue surfaces• Replicates to infectious critical mass• Damage with virulence factors

Materials and Methods

• Kirby Bauer Disk Diffusion Susceptibility Test – 4 bacteria species• Confluent growth

– TSA agar– Impregnate paper disks with 15 μL of oil/water• DI Water control• Eden’s Garden (EOE)• Artisan Aromatics (EOA)• Nature’s Kiss (EOK)• Nature’s Oil (EON)

Photo: Misty Wheeler

Materials and Methods

• Kirby Bauer Disk Diffusion Susceptibility Test– Three replicates – 24 hour incubation at 37o C– Measure zones of inhibition if present

1

2

3 4

EON EOE EOA EOK Water0

2

4

6

8

10

12

B. cereusE. coliS. aureusP. aeruginosa

Treatment

Aver

age

Zone

of I

nhib

ition

(mm

)

Average Zone of Inhibition Per Treatment

Statistical Analyses

• Two-tailed T-tests (α < 0.05) were used to compare the average zones of inhibition between:– Oils vs. DI water control– Oils vs. oils

Results: B. cereus

EON – Natures’ OilEOE – Eden’s GardenEOA – Artisans AromaticsEOK – Nature’s Kiss

P values C EON EOE EOA EOKC EON 0.000043 EOE 0.00041 0.75 EOA 0.00019 0.00071 0.0049 EOK 0.00291 0.0202 0.011 0.14

EON EOE EOA EOK Water0

2

4

6

8

10

12

B. cereusE. coliS. aureusP. aeruginosa

Treatment

Aver

age

Zone

of I

nhib

ition

(mm

)

Average Zone of Inhibition Per Treatment

Results: E. coli

EON – Natures’ OilEOE – Eden’s GardenEOA – Artisans AromaticsEOK – Nature’s Kiss

P values C EON EOE EOA EOKC EON 0.000152 EOE 0.00026 0.81 EOA n/a 0.00015 0.00026 EOK n/a 0.00015 0.00026 n/a

EON EOE EOA EOK Water0

2

4

6

8

10

12

B. cereusE. coliS. aureusP. aeruginosa

Treatment

Aver

age

Zone

of I

nhib

ition

(mm

)

Average Zone of Inhibition Per Treatment

Results: S. aureus

EON – Natures’ OilEOE – Eden’s GardenEOA – Artisans AromaticsEOK – Nature’s Kiss

P value C EON EOE EOA EOKC EON 0.00024 EOE 0.00088 0.101 EOA n/a 0.00024 0.00088 EOK n/a 0.00024 0.00088 n/a

EON EOE EOA EOK Water0

2

4

6

8

10

12

B. cereusE. coliS. aureusP. aeruginosa

Treatment

Aver

age

Zone

of I

nhib

ition

(mm

)

Average Zone of Inhibition Per Treatment

Results: P. aeruginosa

EON – Natures’ OilEOE – Eden’s GardenEOA – Artisans AromaticsEOK – Nature’s Kiss

P value C EON EOE EOA EOKC EON n/a EOE n/a n/a EOA n/a n/a n/a EOK n/a n/a n/a n/a

Summary of Results

• All essential oils showed significant zones of inhibition on:– B. cereus

• Two essential oils (EOE and EON) had significant zones on inhibition on:– S. aureus (Mean = 10.21mm)– E. coli (Mean = 7.77mm)

• No measurable zones on inhibition on – P. aeruginosa

Discussion

• Potential cause for differences: – Gram interactions • B. cereus and S. aureus = Gram positive

– No outer membrane– More susceptible to antibiotics

• E. coli and P. aeruginosa = Gram negative– Purity of oils• Incorrect labeling and advertising

– Problems culturing P. aeruginosa • Passed plates did not grow

Future Directions

• Steam distillation– Requires large amounts of plant material– Small product of essential oil– Analysis of commercial and our oils

Future Directions

• Test more bacteria – Because B. cereus had the largest zones of

inhibition, move on to Bacillus anthracis (common in livestock and occasionally in humans)

Acknowledgements• Dr. April Kay• Dr. Richard Collison• Dr. Dean Turner• MaryAnn McBrayer• Misty Wheeler• Josh Peppers• Amanda Smith• Dr. Jonathan Fisher• DSC Foundation• DSC Vice President of Academic Affairs Office

Questions?

Photo: Misty Wheeler