Most CAP is cured with 5 days of therapy. High severity CAP may require up to 7 days.
Patients should be afebrile for 48hrs and have no more than one sign of clinical instability (SBP100, RR>24, O2 sats<90%, PaO2<60 mmHg on room air) prior to stopping antibiotics.
Cough and chest x-ray abnormalities may take several weeks to resolve. If the patient is otherwise improving and afebrile, extension of antibiotic course is NOT necessary.
Repeated chest x-rays to document resolution of opacities should not be performed sooner than 6 weeks, unless patient’s condition is worsening.
Repeat chest x-rays are warranted if concerned about underlying malignancy (higher risk in smokers and those over 50 years old).
S. pneumoniae bacteremia
Uncomplicated CAP with S. pneumoniae bacteremia includes patients who become afebrile within 72 hours, and have no evidence of necrotizing pneumonia, lung abscess, empyema, or extra-pulmonary disease.
The presence of bacteremia alone does NOT require a prolonged course of parenteral antibiotics. Treat as per usual CAP duration above
S. aureus and Legionella
Pneumonia due to S. aureus or Legionella are exceptions and may require 14 days of antibiotics. Infectious Diseases consultation recommended.
Pneumonia with complications
Necrotizing pneumonia, lung abscess, or empyema will require prolonged therapy.
Respirology and/or Infectious Diseases consultation recommended
Azithromycin 500 mg daily x 3 days
Azithromycin 500 mg once, then 250 mg daily x 4 days
Azithromycin has a long tissue half-life which allows short treatment durations.
Treatment of CAP due to Legionella is the only indication for prolonged azithromycin.