NBDE Microbiology and Pathology 5

Question 1

A Gram-positive, catalase-negative coccus that is optochin-sensitive and bile-soluble is best identified as:

Accepted Answer

Streptococcus pneumoniae

Answer

S. pneumoniae is uniquely optochin-sensitive and bile-soluble, distinguishing it from other alpha-hemolytic streptococci.

Question 2

Which mediator released by mast cells causes immediate vasodilation and increased vascular permeability in acute inflammation?

Accepted Answer

Histamine

Answer

Histamine is preformed in mast cell granules and is released immediately upon IgE cross-linking, causing rapid vasodilation and increased permeability.

Question 3

A central giant cell granuloma of the jaw is best distinguished from a giant cell tumor of bone by which feature?

Accepted Answer

Location in the jaw anterior to the first molar and patient age

Answer

CGCG typically occurs in the jaw anterior to the first molar in patients under 30, whereas giant cell tumor of bone affects epiphyses of long bones in older adults.

Question 4

Necrotizing ulcerative gingivitis (NUG) is most characteristically associated with which combination of organisms?

Accepted Answer

Fusobacterium nucleatum and Treponema vincentii

Answer

NUG (Vincent's angina) is caused by a fusospirochetal complex of Fusobacterium nucleatum and Treponema vincentii in stressed or immunocompromised patients.

Question 5

A painless, fluctuant, blue-domed swelling on the floor of the mouth that transilluminates is most consistent with:

Accepted Answer

Ranula

Answer

A ranula is a mucus retention or extravasation cyst of the sublingual or submandibular gland, presenting as a blue-domed, transilluminant swelling on the floor of the mouth.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Microbiology and Pathology 5