Bacterium
Streptococcus mutans
Dental caries viridans streptococcus
strep-tuh-KOK-us MYOO-tanz
High-yield clue
Uses sucrose to make sticky glucans/dextran that build plaque biofilm on teeth, making it the classic cause of dental caries.
Overview
A viridans-group alpha-hemolytic streptococcus that is the primary teaching agent of dental caries. It illustrates how sucrose metabolism drives biofilm-based disease.
Classification
- Gram-positive
- Cocci in chains
- Alpha-hemolytic
- Viridans group
- Optochin-resistant
Lab & identification clues
- Alpha-hemolytic (green) vocabulary
- Optochin-resistant (contrast with pneumococcus)
- Glucan/dextran production
- Bile-insoluble
Associations
- Dental caries
- Plaque biofilm formation
- Subacute endocarditis (viridans group)
Commonly confused with
- Streptococcus pneumoniae
- Other viridans streptococci
Frequently asked questions
What is Streptococcus mutans?
A viridans-group alpha-hemolytic streptococcus that is the primary teaching agent of dental caries. It illustrates how sucrose metabolism drives biofilm-based disease.
What is the Gram stain of Streptococcus mutans?
Streptococcus mutans is Gram positive.
What are the lab clues for Streptococcus mutans?
Lab clues for Streptococcus mutans include Alpha-hemolytic (green) vocabulary, Optochin-resistant (contrast with pneumococcus), Glucan/dextran production, and Bile-insoluble.
What is Streptococcus mutans commonly confused with?
Streptococcus mutans is commonly confused with Streptococcus pneumoniae and Other viridans streptococci.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.