Question

you complete a capsule stain with the following results.

which of the following is/are correct regarding your stain?

select all that apply.
a. capsules are visible.
b. nigrosin staining was likely omitted.
c. unnecessary heat fixing was performed.
d. counterstaining with crystal violet was likely omitted.

Explanation:

Analyze the capsule stain image

The image shows a capsule stain preparation under a microscope.

• There is a dark/purple background (typically from a negative stain like nigrosin or Congo red, often combined with a simple stain).
• Clear, unstained halos (capsules) are visible surrounding the cells.
• The bacterial cells themselves inside the halos are stained (typically with a basic dye like crystal violet or safranin).
• Since clear halos surrounding stained cells are clearly visible against a colored background, the capsule stain was successful, meaning capsules are visible, and the necessary staining steps (negative staining and counterstaining) were performed.

Evaluate the options

• A. Capsules are visible. Correct. The clear white halos surrounding the purple/pink cells represent the capsules.
• B. Nigrosin staining was likely omitted. Incorrect. The background is colored/dark, indicating a negative background stain was successfully used.
• C. Unnecessary heat fixing was performed. Incorrect. Heat-fixing shrinks or destroys capsules, leading to false negatives or distorted halos. Since clear, well-defined capsules are beautifully preserved and visible, heat-fixing was likely omitted as required by the protocol.
• D. Counterstaining with crystal violet was likely omitted. Incorrect. The cells inside the halos are stained purple/pink, indicating that counterstaining was successfully performed.

Answer:

• A. Capsules are visible. (Correct answer)
• B. Nigrosin staining was likely omitted.
• C. Unnecessary heat fixing was performed.
• D. Counterstaining with crystal violet was likely omitted.