Question

The most common cause of community-acquired pneumonia in adults, regardless of age, is:

A) Mycoplasma pneumoniae
B) Streptococcus pneumoniae
C) Legionella pneumophila
D) Haemophilus influenzae

Answer 1

The most common cause of community-acquired pneumonia in adults is Streptococcus pneumoniae, a gram-positive bacterium known for its virulence and ability to cause severe infections.

Step-by-step explanation:

The most common cause of community-acquired pneumonia in adults is Streptococcus pneumoniae. This gram-positive bacterium is a part of the normal respiratory tract flora and tends to appear in pairs. It colonizes the bronchioles, spreading to the alveoli where it hinders phagocytic clearance. Virulence factors such as pneumolysin O contribute to disease progression, causing inflammatory responses and symptoms like a productive cough with bloody sputum. This infection can result in severe issues if not appropriately treated, and S. pneumoniae is known to cause other serious infections, especially in vulnerable populations like newborns and the immunocompromised.