A patient with poor dental hygiene develops subacute bacterial endocarditis following a dental extraction. Blood culture grows alpha-hemolytic streptococci that are optochin resistant and bile insoluble. Which organism is most likely responsible?
- A Streptococcus pneumoniae
- B Streptococcus agalactiae
- C Streptococcus mutans ✓
- D Enterococcus faecalis
Correct answer: C. Streptococcus mutans
Explanation
Viridans streptococci like Streptococcus mutans are alpha-hemolytic, optochin resistant, and bile insoluble. They are normal oral flora and a common cause of subacute endocarditis after dental procedures. Streptococcus pneumoniae is optochin sensitive. Streptococcus agalactiae is beta-hemolytic. Enterococcus is usually gamma-hemolytic and grows in bile esculin.
Reference: Ananthanarayan and Panicker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.