Streptococcus mutans is best described as which of the following?

Streptococcus mutans is best described as which of the following?

• A. A virus that infects dental enamel
• B. A bacterium responsible for initiating dental caries; breaks down sucrose into glucose and fructose
• C. A fungus that colonizes the mouth
• D. A protozoan in dental plaques

Answer: (D)

Streptococcus mutans is a bacterium. In the mouth, it thrives in dental plaque and is highly acidogenic and aciduric, meaning it produces acid when it metabolizes sugars and can survive in acidic conditions. It contributes to dental caries by fermenting fermentable carbohydrates like sucrose to lactic acid, which lowers the pH near the tooth surface and promotes enamel demineralization. Sucrose is also used by S. mutans to synthesize extracellular polysaccharides (glucans) that help the bacteria adhere to tooth surfaces and to each other, reinforcing the plaque biofilm. Because of these traits—acid production and strong biofilm formation—S. mutans is a major initiator of dental caries. The other options describe viruses, fungi, or protozoa, which are not what Streptococcus mutans is.

Streptococcus mutans is a bacterium. In the mouth, it thrives in dental plaque and is highly acidogenic and aciduric, meaning it produces acid when it metabolizes sugars and can survive in acidic conditions. It contributes to dental caries by fermenting fermentable carbohydrates like sucrose to lactic acid, which lowers the pH near the tooth surface and promotes enamel demineralization. Sucrose is also used by S. mutans to synthesize extracellular polysaccharides (glucans) that help the bacteria adhere to tooth surfaces and to each other, reinforcing the plaque biofilm. Because of these traits—acid production and strong biofilm formation—S. mutans is a major initiator of dental caries. The other options describe viruses, fungi, or protozoa, which are not what Streptococcus mutans is.