Outpatient Treatment of Community Acquired Pneumonia in Adults
By Kevin O. Hwang, MD, MPH
Updated guideline includes recommendations for empiric antibiotics and duration of treatment
Key Points
- For healthy outpatient adults, treat community-acquired pneumonia (CAP) with amoxicillin or doxycycline or a macrolide (if local pneumococcal resistance to macrolides is less than 25%)
- For patients with comorbidities or risk factors for resistant organisms, treat CAP with a combination of [amoxicillin/clavulanate or cephalosporin] AND [macrolide or doxycycline]; alternatively, treat with a respiratory fluoroquinolone alone
- Continue antibiotics until the patient becomes clinically stable and for a minimum of 5 days.
In October 2019 the American Thoracic Society and Infectious Diseases Society of America updated their guideline for the diagnosis and treatment of community-acquired pneumonia (CAP), representing the first such update since 2007. This summary will focus on empiric antibiotics in the outpatient setting as well as duration of treatment.
Choice of antibiotics should be guided by comorbidities that increase the risk for poor outcomes, such as:
- Chronic heart, lung, liver, or renal disease
- Diabetes mellitus
- Alcoholism
- Malignancy
- Asplenia
Antibiotic choice is also influenced by risk factors for antibiotic resistant organisms, such as:
- Prior respiratory isolation of MRSA or P. aeruginosa
- Recent hospitalization AND receipt of parenteral antibiotics in the last 90 days
Healthy Adults
For healthy outpatient adults without comorbidities or risk factors for resistant organisms, the guideline outlines three options:
- Amoxicillin 1 g three times daily is a strong recommendation backed by a moderate quality of evidence
- Doxycycline 100 mg twice daily is a conditional recommendation based on low quality evidence
- A macrolide is acceptable if other options are contraindicated and if the local rate of pneumococcal resistance to macrolides is less than 25%. The doses are azithromycin 500 mg on first day then 250 mg daily, clarithromycin 500 mg twice daily, or clarithromycin ER 1,000 mg daily.
Patients with Comorbidities or Risk Factors for Antibiotic Resistance
Patients with comorbidities or risk factors for resistant organisms would benefit from a broader spectrum of antimicrobial coverage.
- Combination therapy with [Amoxicillin/clavulanate or cephalosporin] AND [macrolide or doxycycline]. The doses are amoxicillin/clavulanate 500 mg/125 mg three times daily or 875 mg/125 mg twice daily or 2,000 mg/125 mg twice daily; cefpodoxime 200 mg twice daily; cefuroxime 500 mg twice daily; azithromycin 500 mg on first day then 250 mg daily; clarithromycin 500 mg twice daily; clarithromycin ER 1,000 mg daily; and doxycycline 100 mg twice daily.
- Monotherapy with respiratory fluoroquinolone. The doses are levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily
The above recommendations for antibiotic options are based on 16 randomized controlled trials (RCTs) in the outpatient setting, RCTs in the inpatient setting, observational studies, antimicrobial resistance trends, and data on antibiotic-related adverse events.
Despite varying levels of evidence supporting the antibiotic options, the guidelines note that the choice of treatment should be based an overall risk-benefit assessment, local epidemiological trends, drug allergies, history of Clostridium difficile, and other conditions such as cardiac arrhythmia (macrolides) and vascular disease (fluoroquinolones). Additionally, patients who have recently received once class of antibiotics should be treated with another class of antibiotics.
Duration of Treatment
The guidelines recommend continuing antibiotics until the patient becomes clinically stable as determined by vital signs, ability to eat, and mental status. The minimum duration of treatment should be 5 days.
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;200(7):e45-e67. https://doi.org/10.1164/rccm.201908-1581ST
