Which counterstain is recommended when Gram-staining Campylobacter jejuni due to poor uptake of safranin?

Which counterstain is recommended when Gram-staining Campylobacter jejuni due to poor uptake of safranin?

• A. Safranin
• B. Crystal violet
• C. Carbolfuchsin
• D. Methylene blue

Answer: (C)

When a bacterium decolorizes easily or does not take up the usual counterstain well, choosing a stain with stronger penetration can restore clear contrast. Campylobacter jejuni is a fragile, Gram-negative organism that often shows poor uptake of safranin, making the pink color hard to see. Carbolfuchsin, a phenolic dye, can penetrate the cell envelope more effectively and provide a vivid red counterstain to decolorized cells. This improves visibility and confirms its Gram-negative nature under light microscopy. The other stains either represent the primary stain used earlier in the process or are not as reliable for this issue, so they don’t provide the same level of contrast for these organisms.

When a bacterium decolorizes easily or does not take up the usual counterstain well, choosing a stain with stronger penetration can restore clear contrast. Campylobacter jejuni is a fragile, Gram-negative organism that often shows poor uptake of safranin, making the pink color hard to see. Carbolfuchsin, a phenolic dye, can penetrate the cell envelope more effectively and provide a vivid red counterstain to decolorized cells. This improves visibility and confirms its Gram-negative nature under light microscopy. The other stains either represent the primary stain used earlier in the process or are not as reliable for this issue, so they don’t provide the same level of contrast for these organisms.