Which may result in Gram-positive bacteria appearing to be Gram-negative?
A) Decolorizing too long AND using young cultures.
B) Decolorizing too short AND using young cultures.
C) Decolorizing too long AND using old cultures.
D) Decolorizing too short AND using old cultures.
E) Forgetting to decolorize AND using old cultures.

Question

Which may result in Gram-positive bacteria appearing to be Gram-negative?
A) Decolorizing too long AND using young cultures.
B) Decolorizing too short AND using young cultures.
C) Decolorizing too long AND using old cultures.
D) Decolorizing too short AND using old cultures.
E) Forgetting to decolorize AND using old cultures.

Quizplus · Accepted Answer

Decolorizing for too long can lead to the removal of the crystal violet-iodine complex from Gram-positive bacteria, making them appear Gram-negative. Using old cultures can also contribute to this issue, as the cell walls of older Gram-positive bacteria may be more permeable or damaged, allowing the stain to be washed out more easily.

Which May Result in Gram-Positive Bacteria Appearing to Be Gram-Negative