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

         1.Fill above table.

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

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

4. Why do you think there is a difference in the sensitivity of the 2 organisms tested with the various chemicals? (Hint: Consider the difference between Gram-negative and Gram-positive bacteria.)

Answer 1

Answer-

According to the given question-

Here we have Chemicals such as Oregano, Thyme, Clove, Lavender, Sage, and Chloramphenicol are tested against the microorganisms E. coli, and S. aureus.

,

	Diameter (mm) E. coli	R / S	Diameter (mm) S. aureus	R / S	Activity Range
Oregano	27	S	54	S	25 - 55
Thyme	26	S	54	S	25 - 55
Clove	14	R	18	S	15 - 30
Lavender	10	R	14	R	15 - 30
Sage	11	R	14	R	15 - 30
Chloramphenicol	14	R	27	S	15 - 30

2- Oregano and Thyme are the chemicals that have the capability to affect both E. coli, and S. aureus and are considered as a “broad spectrum” because they have the capability to prevent the growth or kill the several types of microorganisms belongs to gram-positive as well as gram-negative.

3. Chloramphenicol is the chemicals that have the capability to affect the growth of only one type of microorganism and are considered as a “narrow-spectrum” antibiotics. Chloramphenicol is considered a bacteriostatic for most microorganisms which are Gram-positive and also some of the aerobic bacteria which are Gram-negative but it can be bactericidal against some of the microorganism which is very sensitive.

4. Here we can observe the difference in the sensitivity of antibiotics used for testing both E. coli and S. aureus using various chemicals because gram-positive microorganism has a cell wall made up of a thick layer of peptidoglycan while the gram-negative microorganism has a very thin layer of peptidoglycan, they also have an outer layer made up of LPS or lipopolysaccharide which prevent the entry of several antibiotics, due to these reasons the antibiotics which are effective against gram-positive microorganisms are not effective against the gram-negative microorganisms.