what is the counterstain in the ziehl-neelsen acid-fast stain procedure?
['Step 2: Smear Preparation (Review) ... ', 'Cover the smear with carbolfuchsin dye. ... ', 'Dry heat for 2 minutes.', 'Cool and rinse with water. ... ', 'Wash the top and bottom of slide with water and clean the slide bottom well.', 'Counterstain with Methylene Blue for 30 seconds to 1 minute.']