This protocol addresses adults presenting with community-acquired pneumonia (CAP) who are managed in the outpatient setting. It applies to patients who have no comorbidities — no chronic heart, lung, liver, or renal disease; no diabetes mellitus; no alcoholism; no malignancy; and no asplenia — and who have no risk factors for MRSA or Pseudomonas aeruginosa.
Oral antibiotic therapy is recommended for this population, with agent selection guided in part by local resistance patterns. The full protocol specifies which agents are preferred and for how long treatment should continue.
The primary target is clinical stability: resolution of vital sign abnormalities (heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature), ability to eat, and normal mentation. Most patients reach stability within 48 to 72 hours; antibiotic therapy continues until stability is achieved and for a minimum of 5 days total. Failure to reach clinical stability within 5 days is associated with worse clinical outcomes.
No comorbidities or risk factors for MRSA or Pseudomonas aeruginosa. Comorbidities include chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia. Risk factors include prior respiratory isolation of MRSA or P. aeruginosa or recent hospitalization AND receipt of parenteral antibiotics (in the last 90 d).
For healthy outpatient adults without comorbidities listed below or risk factors for antibiotic resistant pathogens, we recommend (Table 3): 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 <25%.
As recent data supporting antibiotic administration for <5 days are scant, on a risk–benefit basis we recommend treating for a minimum of 5 days, even if the patient has reached clinical stability before 5 days.
We recommend that the duration of antibiotic therapy should be guided by a validated measure of clinical stability (resolution of vital sign abnormalities [heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature], ability to eat, and normal mentation), and antibiotic therapy should be continued until the patient achieves stability and for no less than a total of 5 days. Failure to achieve clinical stability within 5 days is associated with higher mortality and worse clinical outcomes.
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