Treatment for Pneumonia

For outpatient pneumonia in healthy adults, prescribe amoxicillin 1 g orally three times daily for 5–7 days as first-line therapy; for hospitalized non-ICU patients, administer ceftriaxone 1–2 g IV daily plus azithromycin 500 mg daily; and for ICU patients, escalate to ceftriaxone 2 g IV daily plus azithromycin 500 mg IV daily or a respiratory fluoroquinolone.

Severity Assessment and Site-of-Care Decision

Outpatient vs. Inpatient Determination

Use validated severity scores (Pneumonia Severity Index [PSI] or CURB-65) combined with clinical judgment to determine whether hospitalization is required. 1
PSI classes I–III are appropriate for outpatient management unless unstable comorbidities exist; PSI classes IV–V mandate hospitalization. 1, 2
A CURB-65 score ≥ 2 (confusion, urea > 7 mmol/L, respiratory rate ≥ 30/min, blood pressure < 90/60 mmHg, age ≥ 65 years) requires hospital admission. 1, 2
Pulse oximetry must be performed in all suspected cases; documented hypoxemia (SpO₂ < 92 % or PaO₂ < 8 kPa) mandates admission regardless of other criteria. 2

ICU Admission Criteria

ICU admission is indicated when one major criterion (septic shock requiring vasopressors or respiratory failure requiring mechanical ventilation) or ≥ 3 minor criteria are present. 1, 2
Minor criteria include: confusion, respiratory rate ≥ 30/min, systolic BP < 90 mmHg, multilobar infiltrates, PaO₂/FiO₂ < 250, uremia, leukopenia, thrombocytopenia, hypothermia, or need for aggressive fluid resuscitation. 1, 2

Outpatient Treatment

Previously Healthy Adults (No Comorbidities)

Amoxicillin 1 g orally three times daily for 5–7 days is the preferred first-line regimen, retaining activity against 90–95 % of Streptococcus pneumoniae isolates, including many penicillin-resistant strains, and providing superior pneumococcal coverage compared with oral cephalosporins. 2, 3
Doxycycline 100 mg orally twice daily for 5–7 days is an acceptable alternative when amoxicillin cannot be used, offering coverage of both typical and atypical pathogens. 2, 3
Macrolide monotherapy (azithromycin 500 mg day 1, then 250 mg daily; or clarithromycin 500 mg twice daily) should be reserved for regions where pneumococcal macrolide resistance is documented < 25 %; in most U.S. areas resistance is 20–30 %, making macrolides unsafe as first-line agents. 2, 3

Adults with Comorbidities or Recent Antibiotic Use

Patients with chronic diseases (COPD, diabetes, cardiac/hepatic/renal disease, malignancy, immunosuppression) or antibiotic exposure within the prior 90 days require broader coverage. 2, 3
Combination therapy: amoxicillin-clavulanate 875/125 mg orally twice daily plus azithromycin (500 mg day 1, then 250 mg daily) or doxycycline 100 mg twice daily for 5–7 days. 2, 3
Respiratory fluoroquinolone monotherapy: levofloxacin 750 mg orally once daily or moxifloxacin 400 mg orally once daily for 5–7 days is reserved for patients with β-lactam contraindications, acknowledging FDA warnings for tendon rupture, peripheral neuropathy, and aortic dissection. 2, 3

Critical Outpatient Pitfalls

Never use macrolide monotherapy in regions where pneumococcal macrolide resistance exceeds 25 %; this leads to breakthrough bacteremia and treatment failure. 2, 3
Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient pneumonia due to FDA safety warnings and resistance concerns. 2, 3
Oral cephalosporins (cefuroxime, cefpodoxime) should not be first-line due to inferior in-vitro activity against S. pneumoniae, lack of atypical coverage, and higher cost without demonstrated clinical superiority. 2, 3

Hospitalized Non-ICU Patients

Standard Empiric Regimen

Ceftriaxone 1–2 g IV once daily plus azithromycin 500 mg IV or orally daily is the guideline-recommended regimen, providing coverage for typical pathogens (S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis) and atypical organisms (Mycoplasma, Chlamydophila, Legionella). 1, 2, 3
Acceptable β-lactam alternatives include cefotaxime 1–2 g IV every 8 hours or ampicillin-sulbactam 3 g IV every 6 hours, always combined with azithromycin. 1, 2, 3
Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) is equally effective but should be limited to patients allergic to penicillins. 1, 2, 3

Penicillin-Allergic Patients

For documented penicillin allergy, use a respiratory fluoroquinolone (levofloxacin or moxifloxacin) as the preferred alternative. 2, 3
If fluoroquinolones are also contraindicated, use aztreonam 2 g IV every 8 hours plus azithromycin 500 mg IV daily. 2, 3

Critical Timing

Administer the first antibiotic dose in the emergency department immediately upon diagnosis; delays beyond 8 hours increase 30-day mortality by 20–30 % in hospitalized patients. 2, 3
Obtain blood cultures and sputum Gram stain/culture before starting antibiotics to enable pathogen-directed therapy and safe de-escalation. 2, 3

ICU Patients (Severe CAP)

Mandatory Combination Therapy

Ceftriaxone 2 g IV once daily plus azithromycin 500 mg IV daily (or a respiratory fluoroquinolone) is required for all ICU patients; β-lactam monotherapy is linked to significantly higher mortality in critically ill patients with bacteremic pneumococcal pneumonia. 1, 2, 3
Alternative ICU regimen: ceftriaxone 2 g IV daily plus levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily. 2, 3
For penicillin-allergic ICU patients: aztreonam 2 g IV every 8 hours plus levofloxacin 750 mg IV daily. 2, 3

Rationale for Combination Therapy

Combination therapy provides synergistic pathogen coverage and lowers mortality in critically ill patients with bacteremic pneumococcal pneumonia. 1, 2
Fluoroquinolone monotherapy in ICU patients is associated with increased mortality; combination regimens reduce this risk. 1, 2

Special Pathogen Coverage

Pseudomonas aeruginosa Risk Factors

Add antipseudomonal therapy only when specific risk factors are present: structural lung disease (bronchiectasis, cystic fibrosis), recent hospitalization with IV antibiotics within 90 days, prior respiratory isolation of P. aeruginosa, or chronic broad-spectrum antibiotic exposure (≥ 7 days in the past month). 1, 2, 3
Dual antipseudomonal regimen: antipseudomonal β-lactam (piperacillin-tazobactam 4.5 g IV every 6 hours, cefepime 2 g IV every 8 hours, imipenem 500 mg IV every 6 hours, or meropenem 1 g IV every 8 hours) plus a fluoroquinolone (ciprofloxacin 400 mg IV every 8 hours or levofloxacin 750 mg IV daily) plus an aminoglycoside (gentamicin or tobramycin 5–7 mg/kg IV daily). 1, 2, 3

MRSA Risk Factors

Add MRSA coverage only when documented risk factors are present: prior MRSA infection/colonization, recent hospitalization with IV antibiotics within 90 days, post-influenza pneumonia, or cavitary infiltrates on imaging. 2, 3
MRSA regimen: vancomycin 15 mg/kg IV every 8–12 hours (target trough 15–20 µg/mL) or linezolid 600 mg IV every 12 hours, added to the base CAP regimen. 2, 3

Duration of Therapy and Transition to Oral Agents

Minimum Duration

Treat for a minimum of 5 days and continue until the patient is afebrile for 48–72 hours with no more than one sign of clinical instability (temperature ≤ 37.8 °C, heart rate ≤ 100 bpm, respiratory rate ≤ 24 breaths/min, systolic BP ≥ 90 mmHg, SpO₂ ≥ 90 % on room air, able to maintain oral intake, normal mental status). 1, 2, 3
For uncomplicated CAP, a total course of 5–7 days is typical. 1, 2, 3
Extended courses (14–21 days) are required only for infections caused by Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli. 1, 2, 3

IV-to-Oral Transition

Switch from IV to oral antibiotics when the patient is hemodynamically stable (SBP ≥ 90 mmHg, HR ≤ 100 bpm), clinically improving, afebrile 48–72 hours, respiratory rate ≤ 24 breaths/min, SpO₂ ≥ 90 % on room air, and able to take oral medication—typically by hospital day 2–3. 1, 2, 3
Oral step-down options include amoxicillin 1 g three times daily plus azithromycin 500 mg daily, or continuation of azithromycin alone after 2–3 days of IV therapy. 2, 3

Monitoring and Management of Treatment Failure

Routine Monitoring

Monitor temperature, respiratory rate, pulse, blood pressure, mental status, and oxygen saturation at least twice daily in hospitalized patients to detect early deterioration. 1, 2
Outpatients should be reviewed at 48 hours (or sooner if symptoms worsen) to assess response, oral intake, and adherence. 2

Treatment Failure Recognition

If no clinical improvement by day 2–3, obtain repeat chest radiograph, inflammatory markers (CRP, white blood cell count), and additional microbiologic specimens to evaluate for complications (pleural effusion, empyema, lung abscess) or resistant organisms. 1, 2
For outpatient failure of amoxicillin monotherapy, add or substitute a macrolide to cover atypical pathogens. 2
For outpatient failure of combination therapy, switch to a respiratory fluoroquinolone. 2
Hospitalized patients failing initial therapy require chest CT to identify unsuspected complications and reassessment of risk factors that may necessitate broader antimicrobial coverage. 2

Special Populations

Pregnant Women

For pregnant women with pneumonia, use ceftriaxone 1–2 g IV daily plus azithromycin 500 mg daily; avoid fluoroquinolones due to teratogenic risk. 2
In pregnant patients with anaphylactic penicillin allergy, use aztreonam 2 g IV every 8 hours plus azithromycin 500 mg daily. 2

Children

Pediatric pneumonia treatment is beyond the scope of adult guidelines; consult pediatric infectious disease specialists for age-appropriate regimens. 2

Immunocompromised Patients

Immunocompromised adults have higher risk of resistant organisms (Pseudomonas, MRSA), atypical pathogens, and treatment failure, mandating combination therapy or broader-spectrum agents. 2
For immunocompromised patients with β-lactam allergy, use levofloxacin 750 mg orally or IV once daily or moxifloxacin 400 mg orally or IV once daily. 2

Common Pitfalls to Avoid

Do not use macrolide monotherapy in hospitalized patients—it fails to cover typical pathogens like S. pneumoniae and is linked to treatment failure. 2, 3
Do not use β-lactam monotherapy in ICU patients; combination therapy reduces mortality. 1, 2, 3
Reserve broad-spectrum antipseudomonal or MRSA agents for patients with documented risk factors to prevent unnecessary resistance, adverse effects, and cost. 2, 3
Do not delay antibiotic administration while awaiting culture results; specimens should be collected rapidly, but therapy must start immediately. 2, 3
Do not extend therapy beyond 7–8 days in responding patients without specific indications, as longer courses increase antimicrobial resistance risk without improving outcomes. 1, 2

Follow-Up and Prevention

Schedule a routine follow-up visit at 6 weeks for all patients; obtain a chest radiograph only if symptoms persist, physical findings remain abnormal, or the patient has high risk for underlying malignancy (e.g., smokers > 50 years). 2
Offer pneumococcal polysaccharide vaccination to all adults ≥ 65 years and those with high-risk conditions. 2
Recommend annual influenza vaccination for all patients. 2
Provide smoking-cessation counseling to all current smokers. 2

How should pneumonia be treated, including severity assessment and appropriate antibiotic regimens for outpatients, hospitalized non‑ICU patients, ICU patients, children, and pregnant women?

Help us tailor your experience