What is the initial treatment for pneumonia?

Initial Treatment for Pneumonia

The initial empiric antibiotic therapy for pneumonia should be based on the patient's risk factors, severity of illness, and treatment setting, with amoxicillin as first-line therapy for community-acquired pneumonia in outpatients and a β-lactam plus a macrolide for hospitalized patients. 1, 2

Outpatient Treatment

Previously Healthy Adults (No Comorbidities)

• For previously healthy adults with no risk factors for drug-resistant pathogens, a macrolide (e.g., azithromycin) is recommended as first-line therapy 1
• Amoxicillin 1 g every 8 hours is also recommended as a first-line option for outpatients without comorbidities 2
• Doxycycline 100 mg twice daily is an alternative first-line option, with an initial dose of 200 mg to achieve adequate serum levels more rapidly 2

Outpatients with Comorbidities or Recent Antibiotic Use

• A respiratory fluoroquinolone (e.g., levofloxacin, moxifloxacin) or a β-lactam plus a macrolide is recommended 1, 2
• Patients with recent exposure to one class of antibiotics should receive treatment with antibiotics from a different class due to increased risk for bacterial resistance 2

Hospitalized Non-ICU Patients

• Standard regimen options include β-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin) 1, 2
• A respiratory fluoroquinolone alone (levofloxacin or moxifloxacin) is an alternative treatment option 1, 2
• The first antibiotic dose should be administered while still in the emergency department, with early administration associated with improved outcomes 3, 2

Severe CAP/ICU Treatment

Without Risk Factors for Pseudomonas

• A β-lactam plus either a macrolide or a respiratory fluoroquinolone is recommended 1, 2
• Non-antipseudomonal cephalosporin III plus macrolide, or moxifloxacin/levofloxacin with or without a non-antipseudomonal cephalosporin III are recommended options 1, 2

With Risk Factors for Pseudomonas

• An antipseudomonal β-lactam (e.g., piperacillin-tazobactam) plus either ciprofloxacin or levofloxacin is recommended 2
• Alternatively, an antipseudomonal cephalosporin or acylureidopenicillin/β-lactamase inhibitor or carbapenem PLUS ciprofloxacin OR macrolide plus aminoglycoside can be used 1, 2
• For nosocomial pneumonia, piperacillin-tazobactam at a dosage of 4.5 grams every six hours plus an aminoglycoside is recommended 4

Timing and Duration of Therapy

• Antibiotic treatment should be initiated immediately after diagnosis of CAP 1, 2
• The minimum duration of therapy is 5 days for most patients 3, 1, 2
• Patients should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing therapy 3, 1
• Treatment should generally not exceed 8 days in a responding patient 2
• Patients can be switched from intravenous to oral therapy when they are hemodynamically stable, improving clinically, able to ingest medications, and have a normally functioning gastrointestinal tract 3

Special Considerations

• Once the etiology of CAP has been identified, antimicrobial therapy should be directed at that specific pathogen 3, 1
• For Legionella spp., levofloxacin, moxifloxacin, or a macrolide (preferably azithromycin) with or without rifampicin is recommended 1
• For atypical pathogens (Mycoplasma, Chlamydophila), macrolides, doxycycline, or respiratory fluoroquinolones are recommended 1
• Add vancomycin or linezolid when community-acquired MRSA is suspected, with risk factors including prior MRSA infection, recent hospitalization, or recent antibiotic use 2

Common Pitfalls and Caveats

• Overreliance on fluoroquinolones can lead to resistance; they should be reserved for patients with β-lactam allergies or when specifically indicated 2
• Inadequate coverage for atypical pathogens should be avoided, ensuring coverage for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila 2
• Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 2
• Short-course antibiotic regimens (≤7 days) are as effective as extended-course regimens (>7 days) for mild to moderate community-acquired pneumonia, which may help limit antimicrobial resistance 5
• Initial adequate antibiotic therapy is significantly associated with better survival, particularly in patients with Streptococcus pneumoniae CAP or septic shock 6