Microbiology and Pathology Flashcards

Which virulence factor of Streptococcus mutans is most responsible for its adhesion to smooth tooth surfaces?

Answer: Glucosyltransferase (GTF)

Glucosyltransferase synthesizes water-insoluble glucans that mediate S. mutans adhesion to smooth enamel surfaces.

A patient presents with white plaques on the buccal mucosa that can be wiped off, leaving a red, bleeding base. The most likely causative organism is:

Answer: Candida albicans

Pseudomembranous candidiasis (thrush) presents as removable white plaques caused by Candida albicans overgrowth.

The Gram-negative anaerobe most strongly associated with adult periodontitis is:

Answer: Porphyromonas gingivalis

Porphyromonas gingivalis is a keystone pathogen in chronic periodontitis, producing gingipains that destroy periodontal tissue.

A biopsy of a submandibular mass shows 'sulfur granules' surrounded by neutrophils. The causative organism is best described as:

Answer: Filamentous Gram-positive bacterium

Actinomyces israelii, a filamentous Gram-positive bacterium, forms sulfur granules characteristic of cervicofacial actinomycosis.

Which type of hypersensitivity reaction is responsible for the pathogenesis of contact stomatitis from dental materials?

Answer: Type IV (delayed-type)

Contact stomatitis from dental materials (e.g., nickel, eugenol) is mediated by T-lymphocytes in a Type IV delayed hypersensitivity reaction.

A lesion biopsy shows an epithelial lining with a band of hyaline (Rushton) bodies. This finding is most consistent with:

Answer: Radicular cyst

Rushton bodies are hyaline structures found within the epithelial lining of radicular (periapical) cysts.

Which cell type is the primary mediator of chronic granulomatous inflammation as seen in periapical granulomas?

Answer: Macrophage/epithelioid cell

Granulomas are composed primarily of activated macrophages (epithelioid cells) that wall off persistent antigens.