What is the first line treatment for pneumonia?

First-Line Treatment for Pneumonia

For outpatients with community-acquired pneumonia (CAP), start amoxicillin monotherapy; for hospitalized non-severe CAP, use amoxicillin plus a macrolide; and for severe CAP requiring ICU admission, use a broad-spectrum β-lactamase stable antibiotic combined with a macrolide. 1, 2

Community-Acquired Pneumonia (CAP)

Outpatient/Community Setting

• Amoxicillin monotherapy is the first-line treatment for patients managed in the community setting 1, 2
• This recommendation comes from the American College of Physicians and American Thoracic Society guidelines 1, 2

Hospitalized Non-Severe CAP

• Combined oral therapy with amoxicillin and a macrolide (such as azithromycin) is preferred for hospitalized patients without severe disease 1, 2
• Recent evidence from JAMA supports β-lactam/macrolide combination therapy (e.g., ceftriaxone combined with azithromycin) for hospitalized patients without risk factors for resistant bacteria 3

Severe CAP Requiring ICU Admission

• An intravenous combination of a broad-spectrum β-lactamase stable antibiotic together with a macrolide is recommended by the British Thoracic Society 2
• This addresses both typical and atypical pathogens that cause severe pneumonia 1, 2

Special Populations with Pseudomonas Risk

• For patients with risk factors for Pseudomonas aeruginosa, use an antipseudomonal cephalosporin, acylureidopenicillin/β-lactamase inhibitor, or carbapenem plus either ciprofloxacin or a macrolide with an aminoglycoside 1, 2

Alternative Regimens

• For patients intolerant of β-lactams or macrolides, use a fluoroquinolone with enhanced activity against S. pneumoniae together with intravenous benzylpenicillin 1, 2
• Fluoroquinolones should be reserved for selected cases due to resistance concerns and side effects 2

Hospital-Acquired Pneumonia (HAP)

Risk Stratification Approach

The Infectious Diseases Society of America recommends empiric therapy based on mortality risk and MRSA likelihood 1:

Low Mortality Risk Without MRSA Factors

• Monotherapy with piperacillin-tazobactam, cefepime, levofloxacin, imipenem, or meropenem 1

Low Mortality Risk With MRSA Factors

• Add MRSA coverage with vancomycin or linezolid to the above regimens 1

High Mortality Risk or Recent IV Antibiotics

• Use two antipseudomonal agents from different classes plus MRSA coverage 1
• For nosocomial pneumonia, piperacillin-tazobactam should be dosed at 4.5 grams every six hours plus an aminoglycoside 4

Treatment Duration

• 7 days of appropriate antibiotics for non-severe and uncomplicated pneumonia 1, 2
• 10 days for severe microbiologically undefined pneumonia 1, 2
• 14-21 days where Legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia are suspected or confirmed 1, 2
• For hospitalized patients with bacterial CAP, a minimum of 3 days of treatment is recommended 3

Treatment Failure Management

If patients fail to improve as expected 1, 2:

• For those on amoxicillin monotherapy: add a macrolide 1, 2
• For those on combination therapy: change to a fluoroquinolone with effective pneumococcal coverage 1, 2
• Consider adding rifampicin for severe pneumonia not responding to combination antibiotic treatment 2
• Conduct a careful review of clinical history, examination, prescription chart, and investigation results 1, 2

Critical Pitfalls to Avoid

• Never use two β-lactams together when dual coverage is needed for high-risk HAP 1
• Ensure MSSA coverage is included if MRSA coverage is omitted in HAP regimens 1
• Avoid fluoroquinolones as first-line except in specific circumstances, given resistance concerns 1
• Test all patients for COVID-19 and influenza when these viruses are common in the community, as their diagnosis may affect treatment and infection prevention strategies 3
• Consider systemic corticosteroid administration within 24 hours of development of severe CAP, as it may reduce 28-day mortality 3