Question

the most common cause of a community acquired pneumonia is:
streptococcus pneumoniae
klebsiella pneumoniae
staphylococcal pneumoniae
mycoplasma pneumoniae

Explanation:

Community - acquired pneumonia (CAP) is pneumonia that develops in people who live in the community. Streptococcus pneumoniae is the most common bacterial pathogen causing CAP. Klebsiella pneumoniae is more likely to cause hospital - acquired pneumonia or in patients with certain risk factors like alcoholism. Staphylococcal pneumonia can occur, especially after viral infections like influenza, but it is not as common as Streptococcus pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia (not the most common overall for CAP).

Answer:

Streptococcus pneumoniae