**Question:** Vincent's angina is caused by Borrelia vincenti along with-

A. Streptococcus pyogenes
B. Haemophilus influenzae
C. Peptostreptococcus magnus
D. Fusobacterium nucleatum

**Core Concept:** Vincent's angina is a type of periodontitis (inflammation of the gums and periodontal structures) caused by the bacterium Borrelia vincenti. This condition is often associated with other anaerobic bacteria.

**Why the Correct Answer is Right:**
Borrelia vincenti is the primary pathogen responsible for Vincent's angina. It is a spirochete bacterium that can cause severe periodontal infections. Its involvement in the disease is crucial.

**Why Each Wrong Option is Incorrect:**
A. Streptococcus pyogenes (Group A Streptococcus) is a different bacterium unrelated to Vincent's angina. Streptococcal infections are typically caused by Streptococcus pyogenes and not Borrelia vincenti.
B. Haemophilus influenzae is another bacterium commonly associated with respiratory infections and meningitis, not periodontal diseases.
C. Peptostreptococcus magnus is an anaerobic bacterium, but it is not the primary causative agent of Vincent's angina. Its presence might contribute to the infection, but it is not the primary pathogen.
D. Fusobacterium nucleatum is another anaerobic bacterium that can cause periodontal infections. However, it is not specific to Vincent's angina and is often found in combination with other bacteria.

**Clinical Pearl:** Vincent's angina is a rare but severe periodontal infection that requires prompt diagnosis and treatment. The disease is typically associated with a combination of anaerobic bacteria, which makes it challenging to diagnose without considering a comprehensive microbial profile.

**Correct Answer:** C. Peptostreptococcus magnus

**Why This is Right:** Peptostreptococcus magnus is an anaerobic bacterium often found in periodontal infections, including Vincent's angina. While not the primary causative agent, its presence contributes to the severity of the infection and should be considered in the diagnostic process.