Each of the following statements concerning the gram stain is correct except A. Mycobacteria tuberculosis stains blue bacteria it has a thick lipid layer B. Myoplasma pneumonia is not visible in the gram’s stain because it does not have a cell wall C. Streptococcus pyogens stains blue because it has a thick peptidoglycan layer D. Escherichia coli stains pink because it has a thin peptidoglycan layer

Each of the following statements concerning the gram stain is correct except
A. Mycobacteria tuberculosis stains blue bacteria it has a thick lipid layer
B. Myoplasma pneumonia is not visible in the gram’s stain because it does not have a cell wall
C. Streptococcus pyogens stains blue because it has a thick peptidoglycan layer
D. Escherichia coli stains pink because it has a thin peptidoglycan layer

Top of Form

Answer

• A. Mycobacteria tuberculosis stains blue bacteria it has a thick lipid layer
  Explanation:
  Gram stain is not used against mycobacterium tuberculosis simply because this bacteria has high concentration of mycolic acids on the cell wall as well as high GC content in their DNA. These prevents penetration of gram stain and presence of hydrophobic lipids on the cell wall also prevents any variable results or staining. The type of stain that is effective against such a bacteria is an acid-fast bacteria.