What is the first line treatment for pneumonia?

First-Line Treatment for Pneumonia

For outpatient community-acquired pneumonia (CAP), start amoxicillin monotherapy; for hospitalized non-severe CAP, use amoxicillin plus a macrolide; for severe CAP requiring ICU admission, use intravenous broad-spectrum β-lactam plus macrolide; and for hospital-acquired pneumonia (HAP) without high mortality risk or MRSA factors, use piperacillin-tazobactam, cefepime, levofloxacin, imipenem, or meropenem. 1

Community-Acquired Pneumonia (CAP)

Outpatient Setting

• Amoxicillin monotherapy is the first-line treatment for patients with CAP managed in the community setting 1
• This approach targets Streptococcus pneumoniae, the most common bacterial pathogen identified in approximately 15% of CAP cases with known etiology 2

Hospitalized Non-Severe CAP

• Combined oral therapy with amoxicillin and a macrolide (such as azithromycin) is preferred for hospitalized patients without severe disease 1
• β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin, should be administered for a minimum of 3 days in hospitalized patients without risk factors for resistant bacteria 2
• This combination provides coverage for both typical bacterial pathogens and atypical organisms including Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella 1

Severe CAP Requiring ICU Admission

• Intravenous combination of a broad-spectrum β-lactamase stable antibiotic together with a macrolide is recommended 1
• Systemic corticosteroid administration within 24 hours of severe CAP development may reduce 28-day mortality 2

Special Pathogen Considerations

• Test all patients for COVID-19 and influenza when these viruses are circulating in the community, as positive results may affect treatment decisions and infection prevention strategies 2
• For patients with risk factors for Pseudomonas aeruginosa, use an antipseudomonal cephalosporin, acylureidopenicillin/β-lactamase inhibitor, or carbapenem plus either ciprofloxacin or a macrolide with an aminoglycoside 1

Alternative Regimens

• For patients intolerant of β-lactams or macrolides, a fluoroquinolone with enhanced activity against S. pneumoniae together with intravenous benzylpenicillin is an alternative 1
• Fluoroquinolones should be reserved for selected cases due to resistance concerns and side effects 1

Hospital-Acquired Pneumonia (HAP)

Risk Stratification Approach

The choice of empiric therapy depends on mortality risk and MRSA likelihood 3:

Low Mortality Risk Without MRSA Factors:

• Use monotherapy with one of the following 3:
  • Piperacillin-tazobactam 4.5 g IV q6h
  • Cefepime 2 g IV q8h
  • Levofloxacin 750 mg IV daily
  • Imipenem 500 mg IV q6h
  • Meropenem 1 g IV q8h

Low Mortality Risk With MRSA Factors:

• Add MRSA coverage with vancomycin (15 mg/kg IV q8-12h targeting 15-20 mg/mL trough) or linezolid (600 mg IV q12h) to the above regimens 3
• MRSA risk factors include: IV antibiotics in prior 90 days, treatment in units where MRSA prevalence among S. aureus isolates is unknown or >20%, or prior MRSA detection 3

High Mortality Risk or Recent IV Antibiotics:

• Use two antipseudomonal agents from different classes (avoid two β-lactams) plus MRSA coverage 3
• Mortality risk factors include need for ventilatory support due to pneumonia and septic shock 3
• Combination options include a β-lactam (piperacillin-tazobactam, cefepime, ceftazidime, imipenem, or meropenem) plus either a fluoroquinolone (levofloxacin or ciprofloxacin) or aminoglycoside (amikacin, gentamicin, or tobramycin) 3

Nosocomial Pneumonia Specific Dosing

• For nosocomial pneumonia specifically, piperacillin-tazobactam should be dosed at 4.5 grams every six hours plus an aminoglycoside 4
• This higher dose (totaling 18.0 grams daily) differs from the 3.375 gram q6h dosing used for other indications 4

Treatment Duration

• 7 days of appropriate antibiotics for non-severe and uncomplicated pneumonia 1
• 10 days for severe microbiologically undefined pneumonia 1
• 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

Treatment Failure Management

If patients fail to improve as expected 1:

• Conduct careful review of clinical history, examination, prescription chart, and investigation results
• For those on amoxicillin monotherapy, add a macrolide
• For those on combination therapy, change to a fluoroquinolone with effective pneumococcal coverage
• Consider adding rifampicin for severe pneumonia not responding to combination antibiotic treatment

Critical Pitfalls to Avoid

• Do not delay antibiotic administration while awaiting diagnostic test results, as starting adequate antibiotic therapy as soon as possible is the primary goal 5
• Avoid using fluoroquinolones as first-line except in specific circumstances, given resistance concerns 1
• Do not use two β-lactams together when dual coverage is needed for high-risk HAP 3
• Ensure MSSA coverage is included if MRSA coverage is omitted in HAP regimens 3
• Monitor for neuromuscular excitability or seizures in patients receiving higher doses of piperacillin-tazobactam, especially with renal impairment 4