Question

	Diameter (mm) E. coli	R/S	Diameter (mm) S. aureus	R/S	Activity Range
Oregano	27		54
Thyme	26		54
Clove	14		18
Lavender	10		14
Sage	11		14
Chloramphenicol	14		27

Use the table to answer the following 6 questions about essential oils.

1. Do essential oils appear to have the possibility of having some practical antibacterial use? Explain your reasoning.

2. What could be some of the impracticalities and/or problems of using essential oils as an antibacterial agent given the information presented? Explain.

3. What more would you need to study in order to determine if an essential oil was safe and effective to be used specifically as a disinfectant? As an antiseptic?

4. Which of the chemicals appear to affect both types of cells and would be considered “broad spectrum”? Explain your reasoning.

5. Which of the chemicals appear to affect one type of cell and would be considered “narrow spectrum”? Explain your reasoning.

Answer 1

1) The diameters in the table define the ability of the essential oils to inhibit the growth of the bacteria in the media. With the diameters being as broad as upto 54mm, the essential oils do have the ability to inhibit the growth of the bacterium and act as potential antibacterial agents.

2) Some of the problems that can be seen by using essential oils are :

• too much use may become toxic enough
• can cause allergies if used on skin and is not appropriate
• can sometimes make the bacteria resistant to the oils and thus fail in inhibiting the growth.

3) To study if the essential oils are safe and effective as a disinfectant : MBC test can be done. The MBC tests for the minimum bactericidal concentration where the antibiotic acts to kill the growth of bacterial culture.
To study if the essential oils are safe and effective as antiseptic : MIC can be done which tests for the minimal concentration to inhibit the growth of the bacteria and not act harmful.

4) Broad spectrum antibiotics are those that can act on a varied number of microorganisms both Gram positive and negative. The oregano, thyme and clove act with almost huge strengths in both the bacteria and can be said as broad spectrum ones.

5) Narrow specturm antibiotics act in smaller groups of organisms and are limited in effect. The chloramphenicol is narrow spectrum in nature.