Adult Outpatients: Respiratory Tract Infections: Community-acquired Pneumonia


Doses provided in this table are for patients with normal renal and hepatic function. Click on drug link to go to dosing guidelines.  Some antimicrobials are restricted (ID-R).  Click on link for guidelines on obtaining authorization.


Common Pathogens

Drug(s) of First Choice


Community-acquired Pneumonia (CAP) 


S. pneumoniae

M. pneumoniae

C. pneumoniae

Respiratory viruses

Legionella spp.

C. psittaci


H. influenzae (if patient has co-morbidity)

No recent antibiotic therapy:

Doxycycline 100 mg PO BID X 7 days


Azithromycin 500 mg PO daily X 1 day; then 250 mg PO daily X 4 days


Recent antibiotic therapy or patients with co-morbidities:

Levofloxacin 750 mg PO daily X 5 days


MoxifloxacinID-R: SFGH 400 mg PO daily X 7 days


Alternatively the combination of:

Amoxicillin (High-dose) 1 g PO TID X 7 days


Doxycycline 100 mg PO BID X 7 days


Azithromycin  500 mg PO daily X 1; then 250 mg PO daily X 4 days]

Previous antibiotic therapy within last 3 month should be elicited from patient. A course of antibiotics is a risk factor for drug resistance. Recent use of a fluoroquinolone should dictate selection of a non-fluoroquinolone regimen, and vice versa.


Careful follow-up highly recommended. 

Anaerobic lung infection


Amoxicillin/clavulanate 875 mg/125 mg PO BID


Clindamycin 300 mg PO TID