Case: Well, I won't put one here except to say know the most common bugs of pneumonia, a favorite of clinics/boards due to its severity. But tell me, how can I tell the diff. between say, S. pneumoniae pneumonia and a viral pneumonia?
A) So key, LISTEN...both viral and bacterial bugs can cause pneumonia, but understand that a viral (or mycoplasma) source has USUALLY more BILATERAL, diffuse, crackles, rhonchi, wheezing of this LOWER respiratory tract infection(s). BUT...a bacterial source points to a more focal or UNILATERAL source, with dullness to percussion, absent breath sounds.
If you suspect a bacterial origin, treat with Penicillin or amoxicillin. But if you think you have S. aureus or H. flu, you need a second or third generation cephalosporin. Recall that "walking pneumoniae" from Mycoplasma needs different coverage like Erythromycin.