What is the recommended treatment for a patient with pneumonia, considering age and potential underlying conditions such as Chronic Obstructive Pulmonary Disease (COPD) or asthma?

Treatment of Pneumonia in Adults

Age-Specific Treatment Approach

For previously healthy adults without comorbidities, amoxicillin 1 g orally three times daily for 5-7 days is the preferred first-line therapy, with doxycycline 100 mg twice daily as an acceptable alternative. 1

Outpatient Treatment by Age and Comorbidity Status

Healthy adults <65 years without comorbidities:

• Amoxicillin 1 g orally three times daily for 5-7 days (preferred first-line) 1
• Doxycycline 100 mg orally twice daily serves as an acceptable alternative 1
• Macrolides (azithromycin 500 mg day 1, then 250 mg daily; or clarithromycin 500 mg twice daily) should only be used in areas where pneumococcal macrolide resistance is documented <25% 1

Adults ≥65 years OR adults with comorbidities (COPD, asthma, diabetes, heart disease, renal disease, malignancy):

• Combination therapy: β-lactam (amoxicillin-clavulanate 875 mg/125 mg twice daily, cefpodoxime, or cefuroxime) PLUS macrolide (azithromycin or clarithromycin) OR doxycycline 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily) 1

Hospitalized Non-ICU Patients (All Ages)

Two equally effective regimens exist with strong evidence:

• β-lactam PLUS macrolide: Ceftriaxone 1-2 g IV daily PLUS azithromycin 500 mg daily 1, 2
• Respiratory fluoroquinolone monotherapy: Levofloxacin 750 mg IV daily OR moxifloxacin 400 mg IV daily 1

For penicillin-allergic patients, respiratory fluoroquinolone is the preferred alternative 1

Severe CAP Requiring ICU Admission (All Ages)

Combination therapy is mandatory for all ICU patients—monotherapy is inadequate for severe disease:

• Ceftriaxone 2 g IV daily (or cefotaxime 1-2 g IV every 8 hours or ampicillin-sulbactam 3 g IV every 6 hours) PLUS azithromycin 500 mg IV daily 1
• Alternative: β-lactam PLUS respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) 1

Special Considerations for COPD and Asthma Patients

Patients with COPD or asthma require combination therapy even in the outpatient setting due to increased risk of Pseudomonas aeruginosa and other resistant pathogens. 3

COPD-Specific Considerations:

• Pseudomonas aeruginosa risk is increased in patients with COPD, mechanical ventilation >8 days, and prior antibiotic use 3
• For COPD patients with structural lung disease, recent hospitalization with IV antibiotics within 90 days, or prior respiratory isolation of P. aeruginosa, use antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS ciprofloxacin or levofloxacin 1
• Combination therapy with drugs having antipseudomonal activity should be used until etiologic diagnosis is established 3

Asthma-Specific Considerations:

• Treat similarly to patients with comorbidities using combination β-lactam/macrolide therapy or respiratory fluoroquinolone monotherapy 1
• Consider viral etiologies (influenza, RSV) more prominently, especially during respiratory virus season 3

Duration of Therapy

Treat for a minimum of 5 days and until the patient is afebrile for 48-72 hours with no more than one sign of clinical instability. 1

• Typical duration for uncomplicated CAP: 5-7 days 1, 2
• Extended duration (14-21 days) required for specific pathogens: Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli 1
• For severe microbiologically undefined pneumonia: 10 days 1

Transition from IV to Oral Therapy

Switch from IV to oral antibiotics when the patient is hemodynamically stable, clinically improving, afebrile for 48-72 hours, able to take oral medications, and has normal GI function—typically by day 2-3 of hospitalization. 1

Oral step-down options:

• Amoxicillin 1 g three times daily PLUS azithromycin 500 mg daily 1
• Amoxicillin-clavulanate 875 mg/125 mg twice daily PLUS azithromycin 1

Critical Timing Considerations

Administer the first antibiotic dose immediately upon diagnosis, ideally while still in the emergency department—delayed administration beyond 8 hours increases 30-day mortality by 20-30% in hospitalized patients. 1, 4

Coverage for Drug-Resistant Pathogens

Add Antipseudomonal Coverage When:

• Structural lung disease present 1
• Recent hospitalization with IV antibiotics within 90 days 1
• Prior respiratory isolation of P. aeruginosa 1
• COPD with mechanical ventilation >8 days 3

Regimen: Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS ciprofloxacin or levofloxacin PLUS aminoglycoside and azithromycin 1

Add MRSA Coverage When:

• Prior MRSA infection/colonization 1
• Recent hospitalization with IV antibiotics 1
• Post-influenza pneumonia 1
• Cavitary infiltrates on imaging 1

Regimen: Add vancomycin 15 mg/kg IV every 8-12 hours (target trough 15-20 mg/mL) OR linezolid 600 mg IV every 12 hours to base regimen 1

Critical Pitfalls to Avoid

• Never use macrolide monotherapy in areas where pneumococcal macrolide resistance exceeds 25%—this leads to treatment failure 1
• Never use macrolide monotherapy for hospitalized patients—this provides inadequate coverage for typical bacterial pathogens like S. pneumoniae 1
• Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient CAP due to FDA warnings about serious adverse events and resistance concerns 1
• Do not delay antibiotics for diagnostic testing in critically ill patients—administer within 2 hours if life-threatening 5
• Do not extend therapy beyond 7 days in responding patients without specific indications—this increases antimicrobial resistance risk 1

Diagnostic Testing for Hospitalized Patients

Obtain blood cultures (two sets from separate sites) and sputum Gram stain/culture before initiating antibiotics in all hospitalized patients. 1, 4

• Test for COVID-19 and influenza when these viruses are circulating in the community 4, 2
• Urinary antigen testing for Legionella pneumophila serogroup 1 should be considered in severe CAP or ICU patients 1

Prevention Strategies

• Pneumococcal polysaccharide vaccine for persons ≥65 years and those with selected high-risk concurrent diseases 1
• Annual influenza vaccination for all patients, especially those with medical illnesses 1
• Smoking cessation for all patients hospitalized with CAP who smoke 1