What are the recommended oral antibiotic regimens for treating pneumonia?

Oral Antibiotic Regimens for Pneumonia

Outpatient Community-Acquired Pneumonia (CAP)

For otherwise healthy adults without comorbidities, amoxicillin 1 g three times daily is the preferred first-line oral antibiotic, with doxycycline 100 mg twice daily as an alternative. 1

Healthy Adults (No Comorbidities)

Preferred regimens:

• Amoxicillin 1 g orally every 8 hours (strong recommendation based on proven efficacy in inpatient CAP studies and excellent safety profile) 1
• Doxycycline 100 mg orally twice daily (consider 200 mg first dose for faster therapeutic levels) 1

Alternative regimen:

• Macrolide monotherapy (azithromycin 500 mg day 1, then 250 mg daily days 2-5; or clarithromycin 500 mg twice daily) - only in areas where pneumococcal macrolide resistance is <25% 1

Adults with Comorbidities

For patients with chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancy; or asplenia, combination therapy or respiratory fluoroquinolone monotherapy is recommended. 1

Combination therapy options:

• Amoxicillin-clavulanate 875/125 mg twice daily OR 2,000/125 mg twice daily PLUS azithromycin (500 mg day 1, then 250 mg daily) or doxycycline 100 mg twice daily 1
• Cefpodoxime 200 mg twice daily OR cefuroxime 500 mg twice daily PLUS macrolide or doxycycline 1

Monotherapy option:

• Levofloxacin 750 mg once daily 1, 2
• Moxifloxacin 400 mg once daily 1
• Gemifloxacin 320 mg once daily 1

Pathogen-Specific Oral Regimens

Streptococcus pneumoniae (Penicillin MIC <2)

Preferred:

• Amoxicillin 1 g orally every 8 hours 1

Alternatives:

• Levofloxacin 750 mg daily 1
• Moxifloxacin 400 mg daily 1
• Doxycycline 100 mg twice daily 1

Mycoplasma pneumoniae

Preferred:

• Doxycycline 100 mg orally twice daily for 7-14 days 1
• Minocycline 200 mg loading dose, then 100 mg twice daily for 7-14 days 1

Alternatives:

• Azithromycin 500 mg day 1, then 250 mg daily for 4 days 1
• Levofloxacin 750 mg daily for 7-14 days 1
• Moxifloxacin 400 mg daily for 7-14 days 1

Chlamydophila pneumoniae

Preferred:

• Azithromycin 500 mg day 1, then 250 mg daily for 4 days 1

Alternatives:

• Clarithromycin 500 mg twice daily for 10 days 1
• Doxycycline 100 mg twice daily for 10 days 1
• Levofloxacin 500-750 mg daily for 7-10 days 1

Legionella species

Preferred:

• Levofloxacin 750 mg daily 1
• Moxifloxacin 400 mg daily 1

Alternatives:

• Azithromycin 1000 mg IV day 1, then 500 mg orally daily 1

Haemophilus influenzae

β-lactamase negative:

• Amoxicillin 1 g every 8 hours 1

β-lactamase positive:

• Amoxicillin-clavulanate 875/125 mg twice daily 1

Staphylococcus aureus (Methicillin-susceptible)

Alternatives for oral therapy:

• Amoxicillin-clavulanate 875/125 mg three times daily 1
• Levofloxacin 750 mg daily 1
• Clindamycin 600 mg every 8 hours 1

Staphylococcus aureus (Methicillin-resistant)

Oral option:

• Linezolid 600 mg twice daily 1

Treatment Duration

For patients achieving clinical stability, treatment duration should be minimized to reduce antibiotic resistance. 1, 2

• Standard CAP: 5 days for levofloxacin 750 mg regimen 1, 2; 5-7 days for other regimens if clinically stable 1
• Azithromycin: 3-5 days depending on formulation 3, 4, 5
• Atypical pathogens: 7-14 days for Mycoplasma/Chlamydia 1
• Treatment should not exceed 8 days in responding patients 2

Clinical stability criteria (must be afebrile for 48 hours AND meet all of the following): temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24 breaths/min, systolic BP ≥90 mmHg, oxygen saturation ≥90%, ability to maintain oral intake, normal mental status 1

Pediatric Oral Regimens (≥6 months)

Community-Acquired Pneumonia

Preferred:

• Amoxicillin 75-100 mg/kg/day in 3 divided doses (if β-lactamase negative pathogens) 1
• Amoxicillin-clavulanate 45 mg/kg/day in 3 doses OR 90 mg/kg/day in 2 doses (if β-lactamase producing) 1

For atypical pathogens:

• Azithromycin 10 mg/kg day 1, then 5 mg/kg daily days 2-5 1, 3, 6

Mycoplasma/Chlamydia in Children

Preferred:

• Azithromycin 10 mg/kg day 1, then 5 mg/kg daily days 2-5 1

Alternatives:

• Clarithromycin 15 mg/kg/day in 2 doses 1
• Doxycycline 2-4 mg/kg/day in 2 doses (for children >7 years) 1

Critical Warnings and Contraindications

Fluoroquinolone Precautions

Avoid fluoroquinolones in patients with:

• History of QT prolongation, torsades de pointes, or congenital long QT syndrome 3
• Uncorrected hypokalemia or hypomagnesemia 3
• Concurrent use of Class IA or III antiarrhythmics 3
• Recent fluoroquinolone exposure (resistance risk) 2
• Vascular disease or elderly patients (increased adverse event risk) 1

Macrolide Warnings

Azithromycin carries risk of:

• QT prolongation and cardiac arrhythmias (similar precautions as fluoroquinolones) 3
• Hepatotoxicity requiring immediate discontinuation if hepatitis signs develop 3
• Should only be used where pneumococcal macrolide resistance is <25% 1

Clostridium difficile Risk

All antibiotics carry risk of C. difficile-associated diarrhea; maintain high suspicion if diarrhea develops during or up to 2 months after treatment. 3

Common Pitfalls

• Do not use macrolide monotherapy in areas with high pneumococcal resistance (≥25%) - this increases treatment failure risk 1
• Do not use fluoroquinolones as first-line in healthy patients without comorbidities - reserve for appropriate risk groups to minimize resistance and adverse events 1
• Do not continue antibiotics beyond clinical stability plus 48 hours afebrile - prolonged courses increase resistance without improving outcomes 1, 2
• Do not assume oral therapy is appropriate for severe pneumonia - patients with hypoxemia, hemodynamic instability, inability to take oral medications, or high-risk features require hospitalization and IV therapy 3