Red Complex Bacteria — MFDS Part 1 MCQ

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ModerateMicrobiologyRed Complex BacteriaMFDS Part 1

In Socransky's classic classification of subgingival microbial complexes, Porphyromonas gingivalis and Tannerella forsythia are grouped with which other organism in the red complex?

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Correct answer: C — Treponema denticola

The correct answer is C, Treponema denticola. Socransky's classic red complex comprises P. gingivalis, T. forsythia and T. denticola and was strongly associated with increased probing depth and bleeding on probing. Fusobacterium nucleatum, Prevotella intermedia and Campylobacter rectus are associated with the orange complex rather than the red complex. Aggregatibacter actinomycetemcomitans is an important periodontal pathogen, particularly in rapidly progressing disease patterns, but it is not one of the three red-complex organisms. Although contemporary sequencing demonstrates that the periodontal microbiome is more complex than this historical grouping, the classic red-complex classification remains established examinable microbiology.

Reference: Holt SC, Ebersole JL. Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia: the "red complex", a prototype polybacterial pathogenic consortium in periodontitis. Periodontology 2000. 2005;38:72–122. https://pubmed.ncbi.nlm.nih.gov/15853938/