Which organism is commonly found in dental plaque as an anaerobic gram-negative diplococcus?

Which organism is commonly found in dental plaque as an anaerobic gram-negative diplococcus?

• A. Veillonella
• B. Bacteroides
• C. Fusobacterium
• D. Peptostreptococcus

Answer: (A)

Veillonella are small, Gram-negative anaerobic cocci that commonly appear in pairs (diplococci) in dental plaque. They are part of the normal oral flora and thrive in the anaerobic environment of plaque. In the plaque ecosystem, Veillonella often metabolizes lactate produced by streptococci, helping to modulate the local acidity by converting lactate into weaker acids like propionate and acetate. This combination of a Gram-negative diplococcus morphology and an association with dental plaque makes Veillonella the organism described. The other organisms listed don’t fit this combination: Bacteroides are Gram-negative anaerobic rods, Fusobacterium are Gram-negative anaerobic fusiform rods, and Peptostreptococcus are Gram-positive cocci.

Veillonella are small, Gram-negative anaerobic cocci that commonly appear in pairs (diplococci) in dental plaque. They are part of the normal oral flora and thrive in the anaerobic environment of plaque. In the plaque ecosystem, Veillonella often metabolizes lactate produced by streptococci, helping to modulate the local acidity by converting lactate into weaker acids like propionate and acetate. This combination of a Gram-negative diplococcus morphology and an association with dental plaque makes Veillonella the organism described.

The other organisms listed don’t fit this combination: Bacteroides are Gram-negative anaerobic rods, Fusobacterium are Gram-negative anaerobic fusiform rods, and Peptostreptococcus are Gram-positive cocci.