Give an example of microbial antagonism in the oral cavity and its consequence.

Give an example of microbial antagonism in the oral cavity and its consequence.

• A. Streptococcus sanguinis produces hydrogen peroxide that inhibits Streptococcus mutans, potentially reducing caries risk.
• B. Streptococcus mutans enhances Streptococcus sanguinis growth, increasing caries risk.
• C. Porphyromonas gingivalis produces endotoxins that promote enamel demineralization.
• D. Lactobacillus casei kills all other oral bacteria.

Answer: (A)

Microbial antagonism in the oral cavity occurs when one member of the community inhibits another, changing the biofilm composition and the resulting disease risk. An example is Streptococcus sanguinis, an early plaque colonizer, producing hydrogen peroxide as a metabolic byproduct. This hydrogen peroxide can inhibit Streptococcus mutans, a key cariogenic contributor, so their interaction reduces the growth of the acid-producing species. The consequence is a potentially lower risk of dental caries because the antagonistic action of the benign inhabitant suppresses a more harmful competitor, leading to a less cariogenic biofilm. Other options don’t fit this antagonism pattern: mutual enhancement would be cooperation rather than inhibition; a virulence factor like endotoxins causing enamel demineralization is a pathogenic effect rather than interspecies inhibition; and a microorganism killing all others isn’t a realistic or typical example of oral microbial interactions that regulate disease risk.

Microbial antagonism in the oral cavity occurs when one member of the community inhibits another, changing the biofilm composition and the resulting disease risk. An example is Streptococcus sanguinis, an early plaque colonizer, producing hydrogen peroxide as a metabolic byproduct. This hydrogen peroxide can inhibit Streptococcus mutans, a key cariogenic contributor, so their interaction reduces the growth of the acid-producing species. The consequence is a potentially lower risk of dental caries because the antagonistic action of the benign inhabitant suppresses a more harmful competitor, leading to a less cariogenic biofilm. Other options don’t fit this antagonism pattern: mutual enhancement would be cooperation rather than inhibition; a virulence factor like endotoxins causing enamel demineralization is a pathogenic effect rather than interspecies inhibition; and a microorganism killing all others isn’t a realistic or typical example of oral microbial interactions that regulate disease risk.