Streptococcus salivarius — MFDS Part 1 MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: A — Tongue dorsum
The correct answer is A, the tongue dorsum. Streptococcus salivarius is a commensal viridans streptococcus with marked tropism for the papillary surface of the dorsal tongue. Human studies have found it predominantly in saliva and on the tongue dorsum, with relatively low recovery from dental plaque; it may be one of the predominant organisms in healthy tongue biofilm. Supragingival tooth surfaces are therefore not its principal habitat. The gingival crevice and subgingival plaque support distinct plaque communities and are also not its characteristic niche. S. salivarius can be recovered from other mucosal surfaces, including buccal mucosa, but the tongue dorsum is the best single answer.
Reference: Sato S, Yoshimitsu-Narita A, Eifuku H, Inoue M. Isolation and some properties of extracellular glucan-producing strains of human oral Streptococcus salivarius. Microbios. 1990;62(251):101–112. https://pubmed.ncbi.nlm.nih.gov/2370836/