Question 1

Which component of the Mycobacterium cell wall is primarily responsible for its acid-fast property in the Kinyoun method?

Accepted Answer

Mycolic acid

Question 2

During the Kinyoun acid-fast staining procedure, what is the main function of the acidified alcohol (3% HCl & 95% Ethyl Alcohol)?

Accepted Answer

To decolorize non-acid-fast bacteria

Question 3

A mixed smear of Mycobacterium gordonae and Staphylococcus aureus is stained using the Kinyoun method. After the procedure, what color would you expect each organism to appear under oil immersion?

Accepted Answer

Mycobacterium gordonae appears red, Staphylococcus aureus appears blue

Question 4

Why is heat fixing considered a critical step in the Kinyoun acid-fast staining procedure?

Accepted Answer

It kills the bacteria and adheres them to the slide

Question 5

Which of the following best explains why Mycobacterium resists decolorization by acidified alcohol in the Kinyoun method?

Accepted Answer

The presence of mycolic acid in the cell wall

Question 6

A student forgets to apply the acidified alcohol during the Kinyoun staining procedure. What is the most likely result when observing a mixed smear of Mycobacterium gordonae and Staphylococcus aureus?

Accepted Answer

Both bacteria will appear red

Question 7

Which stain is used as the primary stain in the Kinyoun acid-fast staining method?

Accepted Answer

Kinyoun Carbol Fuchsin

Question 8

What is the role of methylene blue in the Kinyoun acid-fast staining procedure?

Accepted Answer

It counterstains non-acid-fast bacteria blue

Question 9

Which of the following best describes the appearance of Staphylococcus aureus after Kinyoun acid-fast staining?

Accepted Answer

Blue cocci in clusters

Question 10

A clinical sample is stained using the Kinyoun method and shows slender, red rods clumped together. Which organism is most likely present?

Accepted Answer

Mycobacterium gordonae

Question 11

Which of the following is the correct order of reagents used in the Kinyoun acid-fast staining method?

Accepted Answer

Kinyoun Carbol Fuchsin, Acidified Alcohol, Aqueous Methylene Blue

Question 12

If a laboratory technician uses only 70% ethanol instead of 95% ethanol in the acidified alcohol decolorizer, what is the most likely effect on the staining results?

Accepted Answer

Non-acid-fast bacteria may not be fully decolorized and could appear red

Question 13

Which property of Kinyoun Carbol Fuchsin allows it to penetrate the waxy cell wall of Mycobacterium?

Accepted Answer

It is lipid soluble

Question 14

A patient is suspected of having tuberculosis. Which staining method would be most appropriate for detecting the causative organism in a sputum sample?

Accepted Answer

Kinyoun acid-fast stain

Question 15

Which of the following best explains why Mycobacterium appears weakly Gram-positive but is better identified using the acid-fast stain?

Accepted Answer

The thick mycolic acid layer prevents proper uptake of Gram stain

Question 16

Suppose you are given a slide with a mixed smear of Mycobacterium gordonae and Staphylococcus aureus. After performing the Kinyoun method, you observe only blue cells. Which step was most likely omitted or performed incorrectly?

Accepted Answer

Application of Kinyoun Carbol Fuchsin

Question 17

Which of the following equations best represents the composition of the acidified alcohol used in the Kinyoun method?

Accepted Answer

$$3\%\ \mathrm{HCl} + 95\%\ \mathrm{C_2H_5OH}$$

Question 18

In a clinical scenario, a sample is stained using the Kinyoun method and shows blue cocci in clusters and red rods in clumps. What is the most likely diagnosis?

Accepted Answer

Mixed infection with Staphylococcus aureus and Mycobacterium species

Question 19

Which of the following best describes the mechanism by which acid-fast bacteria repel the counterstain methylene blue?

Accepted Answer

The mycolic acid layer retains the primary stain and prevents entry of the counterstain

Question 20

A laboratory error results in the use of only distilled water (no acidified alcohol) after the primary stain in the Kinyoun method. What is the most likely appearance of Staphylococcus aureus on the slide?

Accepted Answer

Red cocci in clusters

Acid-Fast Staining: The Kinyoun Method (Experiment 10)

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