What are the recommended antibiotics for treating pneumonia?

Recommended Antibiotics for Pneumonia

For community-acquired pneumonia (CAP), the first-line treatment is a respiratory fluoroquinolone (e.g., levofloxacin 750 mg once daily for 5 days) or high-dose amoxicillin (1g three times daily) depending on patient factors and local resistance patterns. 1

Community-Acquired Pneumonia (CAP)

First-line treatments:

• Outpatient treatment (mild-moderate CAP):
  • Immunocompetent patients: Amoxicillin 1g three times daily (3g/day)
  • Immunosuppressed patients: Respiratory fluoroquinolone (e.g., levofloxacin 750 mg once daily for 5 days)
  • Alternative for penicillin-allergic patients: Respiratory fluoroquinolone or macrolide (though macrolides have limited activity against drug-resistant S. pneumoniae)

Inpatient treatment (moderate-severe CAP):

• Standard therapy: β-lactam (ceftriaxone, high-dose amoxicillin) plus a macrolide or respiratory fluoroquinolone
• For patients with risk factors for Pseudomonas:
  • Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, or meropenem) plus either a respiratory fluoroquinolone or an aminoglycoside 1, 2

Nosocomial/Hospital-Acquired Pneumonia

First-line treatment:

• Initial empiric therapy: Piperacillin-tazobactam 4.5g every 6 hours plus an aminoglycoside 2
• Duration: 7-14 days
• For confirmed Pseudomonas aeruginosa: Continue aminoglycoside therapy 2

Pathogen-Specific Considerations

Streptococcus pneumoniae:

• Penicillin-susceptible: β-lactam antibiotics
• Penicillin-resistant: Levofloxacin, high-dose amoxicillin, or ceftriaxone
• Bacteremic pneumococcal pneumonia: Combination therapy for 10-14 days 1

Staphylococcus aureus:

• MSSA: Oxacillin, flucloxacillin, or 1st generation cephalosporin
• MRSA: Vancomycin or linezolid 1

Pseudomonas aeruginosa:

• Recommended: Combination therapy with antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, meropenem) plus either a fluoroquinolone or an aminoglycoside 1, 2, 3

Special Populations

Patients with renal impairment:

• Dose adjustments required for many antibiotics
• For piperacillin-tazobactam:
  • CrCl 20-40 mL/min: 2.25g every 6 hours (non-nosocomial); 3.375g every 6 hours (nosocomial)
  • CrCl <20 mL/min: 2.25g every 8 hours (non-nosocomial); 2.25g every 6 hours (nosocomial) 2

Pregnant women:

• Consider broader coverage with piperacillin-tazobactam, cefepime, or meropenem
• Add vancomycin or linezolid if MRSA risk factors present 1

Treatment Duration and Assessment

• Standard duration for uncomplicated CAP: 5-7 days 1
• Bacteremic pneumococcal pneumonia: Minimum 10-14 days 1
• Nosocomial pneumonia: 7-14 days 2
• Clinical assessment: Evaluate response within 48-72 hours; if no improvement, reevaluate diagnosis and consider alternative pathogens or resistance 1

Important Considerations

• Despite increasing in vitro resistance to penicillins, clinical failures with parenteral penicillin-class antibiotics in pneumococcal pneumonia are rare compared to documented failures with quinolones and macrolides 4
• For patients who have received fluoroquinolones in the past 3 months, consider alternative regimens due to risk of resistance 1
• Combination therapy for severe pneumonia helps prevent emergence of resistant organisms 3
• Vaccination against pneumococcus and influenza is strongly recommended for prevention, especially in high-risk populations 1

Pitfalls to Avoid

• Don't rely solely on macrolides for empiric treatment due to increasing resistance
• Don't continue empiric broad-spectrum coverage without attempting to narrow based on culture results
• Don't fail to reassess therapy within 48-72 hours
• Don't use fluoroquinolones as first-line agents in uncomplicated cases to prevent development of resistance