Empiric antibiotic therapy
Healthy adults without comorbidities should be treated with monotherapy of either:
- Amoxicillin 1 g three times daily.
- OR doxycycline 100 mg twice daily.
- OR a macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily or clarithromycin extended release 1,000 mg daily) only in areas with pneumococcal resistance to macrolides less than 25%.
Adults with comorbidities such as chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia should be treated with:
- Amoxicillin/clavulanate 500 mg/125 mg three times daily, or amoxicillin/ clavulanate 875 mg/125 mg twice daily, or 2,000 mg/125 mg twice daily, or a cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily); and a macrolide (azithromycin 500 mg on first day then 250 mg daily, clarithromycin [500 mg twice daily or extended release 1,000 mg once daily]), or doxycycline 100 mg twice daily. (Some experts recommend that the first dose of doxycycline should be 200 mg.)
- OR monotherapy with respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily).
Inpatient pneumonia that is not severe, without risk factors for resistant organisms should be treated with:
- Beta-lactam (ampicillin 1 sulbactam 1.5-3 g every 6 h, cefotaxime 1-2 g every 8 h, ceftriaxone 1-2 g daily, or ceftaroline 600 mg every 12 h) and a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily).
- OR monotherapy with a respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily).
If there is a contraindication for the use of both a macrolide and a fluoroquinolone, then doxycycline can be used instead.
Severe inpatient pneumonia without risk factors for resistant organisms should be treated with combination therapy of either (agents and doses the same as above):
- Beta-lactam and macrolide.
- OR fluoroquinolone and beta-lactam.
It is recommended to not routinely add anaerobic coverage for suspected aspiration pneumonia unless lung abscess or empyema is suspected. Clinicians should identify risk factors for MRSA or P. aeruginosa before adding additional agents.
Duration of antibiotic therapy is determined by the patient achieving clinical stability with no less than 5 days of antibiotics. In adults with symptom resolution within 5-7 days, no additional follow-up chest imaging is recommended. If patients test positive for influenza, then anti-influenza treatment such as oseltamivir should be used in addition to antibiotics regardless of length of influenza symptoms before presentation.
The bottom line
CAP treatment should be based on severity of illness and risk factors for resistant organisms. Blood and sputum cultures are recommended only for patients with severe pneumonia. There have been important changes in the recommendations for antibiotic treatment of CAP, with high-dose amoxicillin recommended for most patients with CAP who are treated as outpatients. Patients who exhibit clinical stability should be treated for at least 5 days and do not require follow up imaging studies.
For a podcast of this guideline, go to iTunes and download the Infectious Diseases Society of America guideline podcast.
Reference
Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67.
Tina Chuong, DO, is a second-year resident in the family medicine residency program at Abington (Pa.) Jefferson Health. Dr. Skolnik is professor of family and community medicine at Jefferson Medical College, Philadelphia, and an associate director of the family medicine residency program at Abington Jefferson Health.