ACID FAST AND GRAM STAINING (MULTIPLE CHOICE)

• Acid-fast staining is specifically designed for bacteria with waxy cell walls
• Mycolic acids in the cell wall make bacteria resistant to decolorization in acid-fast staining
• Mycobacterium tuberculosis is commonly identified using acid-fast staining
• Two methods used for acid-fast staining are Ziehl-Neelsen and Kinyoun
• In Gram staining, Gram-positive bacteria appear purple
• Peptidoglycan is the component of the Gram-positive cell wall that retains the crystal violet stain
• Escherichia coli bacteria stain pink in Gram staining
• The primary decolorizing agent used in Gram staining is alcohol or acetone or ethanol
• Primary stain used in acid-fast staining: Carbolfuchsin
• Purpose of heating the slide during acid-fast staining:

  • To fix the stain onto the bacterial cell
  • To melt the waxy cell wall of acid-fast bacteria
• Decolorizing agent used in acid-fast staining:

  • Acid-Alcohol
  • H2So4 3% in 95% ethanol
• Counterstain used in acid-fast staining: Methylene blue
• Color of acid-fast bacteria after staining with the primary stain: Red
• Type of bacteria resistant to decolorization in acid-fast staining: Acid-fast bacteria
• Purpose of the counterstain in acid-fast staining: To differentiate acid-fast bacteria from non-acid-fast bacteria
• What is the final step in the acid-fast staining procedure?

  1. Washing the slide with water