Halitosis Microbiology — MFDS Part 1 MCQ

Correct answer: B — Fusobacterium nucleatum and Porphyromonas gingivalis

Fusobacterium nucleatum and Porphyromonas gingivalis are Gram-negative anaerobic organisms associated with intra-oral halitosis. Their metabolism of sulphur-containing amino acids contributes to volatile sulphur compound production, including hydrogen sulphide; P. gingivalis is also an important producer of methanethiol. These gases account for much of the characteristic oral malodour arising from tongue coating and periodontal biofilms. Streptococcus mutans and Lactobacillus acidophilus are primarily associated with dental caries. Streptococcus sanguinis, Streptococcus salivarius and Actinomyces naeslundii are predominantly Gram-positive oral commensals rather than the characteristic Gram-negative anaerobic halitosis-associated pair. Candida albicans is a fungus principally associated with oral candidosis and is not a principal source of volatile sulphur compounds in intra-oral halitosis.

Reference: Li F et al. Evaluation of the antibacterial activity of Elsholtzia ciliate essential oil against halitosis-related Fusobacterium nucleatum and Porphyromonas gingivalis. Frontiers in Microbiology. 2023. https://pubmed.ncbi.nlm.nih.gov/37608950/