Bacterial cells with thick peptidoglycan and numerous teichoic acid cross-linkages are Gram stained. The organisms stain pink. Which one of the following statements explains this discre-pancy?
a. The bacterial cells were most likely not heat-fixed to the slide.
b. The bacterial cells were subjected to the decolorizer too long and were overdecolo-rized.
c. The lot of Gram-stain reagent is most likely expired.
d. No discrepancy exists; cells with this composition stain pink on Gram stain.
B
Bacteria with thick peptidoglycan and numerous teichoic acid croslinkages are gram-positive organisms. If the bacteria are staining gram-negative, the staining process may have resulted in over decolorization making the cells appear pink. If the smear is a primary smear, reviewing the staining of neighboring cells can be used to assist in the interpretation. If other cells that are typ-ically gram-positive in nature, such as gram-positive cocci in clusters, it is possible that the or-ganisms staining pink are no longer viable preventing the crystal violet from remaining in the deteriorating cell walls of dying cells.
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