What is the first line treatment for pneumonia?

First-Line Treatment for Pneumonia

The first-line treatment for community-acquired pneumonia (CAP) is amoxicillin monotherapy for outpatients, and a combination of a β-lactam (such as ceftriaxone) plus a macrolide (such as azithromycin) for hospitalized patients. 1, 2

Treatment Based on Setting and Severity

Outpatient (Non-Severe CAP)

• Amoxicillin monotherapy is recommended for previously untreated patients in the community setting 1
• For patients with risk factors for atypical pathogens, a macrolide (erythromycin or clarithromycin) can be added to amoxicillin 1, 3
• Monotherapy with a macrolide may be suitable for patients who have failed to respond to an adequate course of amoxicillin 1
• Fluoroquinolones are not recommended as first-line agents for community use 1

Hospitalized Patients (Non-Severe CAP)

• Combined oral therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) is preferred 1, 4
• When oral treatment is contraindicated, recommended parenteral choices include intravenous ampicillin or benzylpenicillin, together with erythromycin or clarithromycin 1
• The oral route is recommended when possible, with switch from parenteral to oral as soon as clinical improvement occurs and temperature has been normal for 24 hours 1

Severe CAP Requiring ICU Admission

• Patients should be treated immediately after diagnosis with parenteral antibiotics 1
• An intravenous combination of a broad-spectrum β-lactamase stable antibiotic (co-amoxiclav, cefuroxime, cefotaxime, or ceftriaxone) together with a macrolide (clarithromycin or erythromycin) is preferred 1, 5
• For patients with risk factors for Pseudomonas aeruginosa, an antipseudomonal cephalosporin, acylureidopenicillin/β-lactamase inhibitor, or carbapenem plus either ciprofloxacin or a macrolide with an aminoglycoside is recommended 1

Duration of Treatment

• For non-severe and uncomplicated pneumonia, 7 days of appropriate antibiotics is recommended 1
• For severe microbiologically undefined pneumonia, 10 days of treatment is proposed 1
• Treatment should be extended to 14-21 days where Legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia are suspected or confirmed 1
• Generally, treatment duration should not exceed 8 days in a responding patient 1

Special Considerations

Patients with Penicillin Allergies

• For those intolerant of β-lactams or macrolides, a fluoroquinolone with enhanced activity against S. pneumoniae (such as levofloxacin) together with intravenous benzyl-penicillin is offered as an alternative 1
• Fluoroquinolones should be reserved for selected cases due to concerns about resistance development and side effects 1

Treatment Failure

• For patients who fail to improve as expected, there should be a careful review of the clinical history, examination, prescription chart, and investigation results 1
• When a change in empirical antibiotic treatment is necessary, a macrolide could be added for those treated with amoxicillin monotherapy 1
• For those on combination therapy, changing to a fluoroquinolone with effective pneumococcal coverage is an option 1
• The addition of rifampicin may be considered for severe pneumonia not responding to combination antibiotic treatment 1

Pathogen-Specific Considerations

• If atypical pneumonia is diagnosed or suspected, erythromycin (2-4g daily) or doxycycline (200mg daily) is recommended for Mycoplasma pneumoniae and Chlamydia pneumoniae infections 3
• For Legionella pneumonia, erythromycin 2-4g daily for at least three weeks is preferred 3
• The newest JAMA review (2024) emphasizes that up to 40% of hospitalized patients with an identified pathogen have viral causes, highlighting the importance of testing for COVID-19 and influenza when these viruses are common in the community 2

Common Pitfalls and Caveats

• Failure to cover atypical pathogens in appropriate clinical scenarios can lead to treatment failure 3
• Delaying appropriate antibiotic therapy in severe pneumonia increases mortality 5
• Modifying initially inadequate therapy according to microbiological results may not improve outcomes, emphasizing the importance of appropriate initial empiric therapy 5
• Despite concerns about resistance, there is only a single report of documented microbiologic failure of parenteral penicillin-class antibiotics in pneumococcal pneumonia, while there are numerous reports of treatment failure with quinolone and macrolide antibiotics 4