What is the initial treatment for pneumonia?

Initial Treatment for Pneumonia

The initial treatment for community-acquired pneumonia (CAP) should be a β-lactam plus a macrolide for hospitalized patients, while outpatients can be treated with amoxicillin as first-line therapy or a macrolide for previously healthy adults with no risk factors for drug-resistant pathogens. 1, 2

Treatment Based on Patient Setting

Outpatient Treatment

• Amoxicillin 1g every 8 hours is recommended as first-line therapy for outpatients without comorbidities 2
• Doxycycline 100mg twice daily (with first dose of 200mg) is an alternative first-line option for outpatients without comorbidities 2
• For previously healthy adults with no risk factors for drug-resistant pathogens, a macrolide (e.g., azithromycin) is recommended as first-line therapy 1
• For outpatients with comorbidities or recent antibiotic use, a respiratory fluoroquinolone or a β-lactam plus a macrolide is recommended 1, 2

Hospitalized Non-ICU Patients

• A β-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin) is the standard recommended regimen 1, 2
• A respiratory fluoroquinolone alone (levofloxacin or moxifloxacin) can be used as an alternative treatment option 1, 2
• The first antibiotic dose should be administered while the patient is still in the emergency department 3, 2

Severe CAP/ICU Treatment

• For patients without risk factors for Pseudomonas: β-lactam plus either a macrolide or a respiratory fluoroquinolone 1, 2
• For patients with risk factors for Pseudomonas: antipseudomonal β-lactam plus either ciprofloxacin/levofloxacin or an aminoglycoside plus azithromycin 1, 2
• Consider drotrecogin alfa activated within 24 hours of admission for patients with persistent septic shock despite adequate fluid resuscitation 3

Timing and Duration of Therapy

• Antibiotic treatment should be initiated immediately after diagnosis of CAP 1, 2
• Patients should be treated for a minimum of 5 days 3, 1
• 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
• A longer duration of therapy may be needed if initial therapy was not active against the identified pathogen or if complicated by extrapulmonary infection 3

Switching from IV to Oral Therapy

• Patients should 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
• This switch can typically be considered around day 3 of hospitalization for patients who have clinically stabilized 3
• Patients can be discharged as soon as they are clinically stable, have no other active medical problems, and have a safe environment for continued care 3

Pathogen-Directed Therapy

• Once the etiology of CAP has been identified using reliable microbiological methods, 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

Important Considerations and Pitfalls

• Azithromycin carries risks of QT prolongation, which can be fatal in at-risk groups including patients with known QT prolongation, history of torsades de pointes, congenital long QT syndrome, bradyarrhythmias, or uncompensated heart failure 4
• 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 2
• Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 2
• Initial adequate antibiotic therapy markedly decreases mortality, particularly in patients with Streptococcus pneumoniae CAP or septic shock 5
• Short-course antibiotic regimens (7 days or less) are as effective as extended-course regimens for mild to moderate CAP 6