Q. Each of the following statements concerning the Gram stain is correct except:
- Mycobacterium tuberculosis stains blue because it has a thick lipid layer
- Escherichia coli stains pink because it has a thin peptidoglycan layer
- Streptococcus pyogens stains blue because it has a thick peptidoglycan layer
- Mycoplasma pneumoniae is not visible in the Gram’s stain because it does not have a cell wall
Answer: Mycobacterium tuberculosis stains blue because it has a thick lipid layer
