Which of the following is the most common cause of community-acquired pneumonia (CAP) in adults
Question : Which of the following is the most common cause of community-acquired pneumonia (CAP) in adults?
A. Streptococcus pneumoniae
B. Haemophilus influenzae
C. Legionella pneumophila
D. Mycoplasma pneumoniae
Answer: A
Explanation: Streptococcus pneumoniae is the leading pathogen causing community-acquired pneumonia in adults worldwide, accounting for 30%-50% of cases. Haemophilus influenzae is more common in patients with chronic obstructive pulmonary disease; Legionella pneumophila is associated with waterborne transmission; Mycoplasma pneumoniae is prevalent in adolescents and young adults. Thus, the correct answer is A.
