Is Group B Streptococcus (GBS) Gram positive or Gram negative?

Is Group B Streptococcus (GBS) Gram positive or Gram negative?

• A. Gram negative
• B. Gram positive
• C. Gram variable
• D. Gram non-stainable

Answer: (B)

Streptococcus group B is a Gram-positive organism. Its thick peptidoglycan cell wall retains the crystal violet stain during Gram staining, so it appears purple after staining. This contrasts with Gram-negative bacteria, which have a thinner peptidoglycan layer and an outer membrane, causing them to take up the counterstain and appear pink/red. Some bacteria can show variable staining or be non-stainable, but Group B Streptococcus is consistently Gram-positive, making that the correct characterization.

Streptococcus group B is a Gram-positive organism. Its thick peptidoglycan cell wall retains the crystal violet stain during Gram staining, so it appears purple after staining. This contrasts with Gram-negative bacteria, which have a thinner peptidoglycan layer and an outer membrane, causing them to take up the counterstain and appear pink/red. Some bacteria can show variable staining or be non-stainable, but Group B Streptococcus is consistently Gram-positive, making that the correct characterization.