Treatment of Multifocal Pneumonia
Critical First Step: Determine Timing of Pneumonia Onset
The single most important decision is whether this represents community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP), as treatment algorithms differ fundamentally. 1
- If symptoms began in the community or within 48 hours of hospital admission, treat as CAP 2, 1
- If pneumonia developed ≥48 hours after hospital admission, treat as HAP 2, 1
- An 80-year-old patient has inherently higher mortality risk and requires careful assessment for high-risk features including ventilatory support needs, septic shock, or recent IV antibiotic use within 90 days 1
Treatment Algorithm for Community-Acquired Pneumonia (CAP)
Non-Severe CAP (Hospitalized Elderly Patient)
Combined oral therapy with amoxicillin PLUS a macrolide (erythromycin or clarithromycin) is the preferred empiric regimen for elderly patients requiring hospital admission. 2, 1
- Most hospitalized elderly patients can be adequately treated with oral antibiotics 2, 1
- When oral treatment is contraindicated, use IV ampicillin or benzylpenicillin together with IV erythromycin or clarithromycin 2, 1
- Levofloxacin 750 mg IV/PO daily is an alternative for patients intolerant of penicillins or macrolides 2, 1
Severe CAP (Requires Immediate Parenteral Antibiotics)
Patients with severe pneumonia require immediate IV antibiotics upon diagnosis with a combination of a broad-spectrum β-lactam PLUS a macrolide. 2, 1
The preferred regimen is: 2, 1
- IV co-amoxiclav OR a 2nd/3rd generation cephalosporin (cefuroxime, cefotaxime, or ceftriaxone) PLUS a macrolide (clarithromycin or erythromycin)
Important caveat: Ceftriaxone 1g daily may be inadequate for MSSA pneumonia—prescribing information recommends 2-4g daily for MSSA, and poor outcomes have been documented with 1g dosing 3
Duration of Treatment:
- 10 days for microbiologically undefined severe pneumonia 2, 1
- 14-21 days if Legionella, Staphylococcus aureus, or Gram-negative enteric bacilli are suspected or confirmed 2, 1
Treatment Algorithm for Hospital-Acquired Pneumonia (HAP)
Step 1: Assess MRSA Risk Factors
MRSA coverage is indicated if ANY of the following are present: 2, 1
- IV antibiotic use within the prior 90 days
- Treatment in a unit where MRSA prevalence among S. aureus isolates is >20% or unknown
- High risk of mortality (need for ventilatory support or septic shock)
Step 2: Assess Mortality Risk
High mortality risk includes: 2, 1
- Need for ventilatory support due to pneumonia
- Septic shock
- Recent IV antibiotic use within 90 days
Treatment Regimens Based on Risk Stratification
Low Mortality Risk + No MRSA Risk Factors
Use a single antipseudomonal agent with MSSA coverage: 2, 1
- Piperacillin-tazobactam 4.5g IV q6h, OR
- Cefepime 2g IV q8h, OR
- Levofloxacin 750mg IV daily, OR
- Imipenem 500mg IV q6h, OR
- Meropenem 1g IV q8h
High Mortality Risk OR MRSA Risk Factors Present
Use TWO antipseudomonal agents from different classes (avoid combining two β-lactams) PLUS vancomycin or linezolid for MRSA coverage: 2, 1
Select TWO from different classes:
- β-lactam options: Piperacillin-tazobactam 4.5g IV q6h, Cefepime or ceftazidime 2g IV q8h, Imipenem 500mg IV q6h, Meropenem 1g IV q8h
- Fluoroquinolone options: Levofloxacin 750mg IV daily, Ciprofloxacin 400mg IV q8h
- Aminoglycoside options: Amikacin 15-20 mg/kg IV daily, Gentamicin 5-7 mg/kg IV daily, Tobramycin 5-7 mg/kg IV daily
- Alternative: Aztreonam 2g IV q8h
PLUS MRSA coverage:
- Vancomycin 15 mg/kg IV q8-12h (target trough 15-20 mg/mL; consider loading dose 25-30 mg/kg IV × 1 for severe illness), OR
- Linezolid 600mg IV q12h
Critical Pitfalls to Avoid
- Never use an aminoglycoside as the sole antipseudomonal agent 2
- Do not combine two β-lactam antibiotics when dual antipseudomonal coverage is needed 2
- Ceftriaxone 1g daily is inadequate for MSSA pneumonia—use higher doses (2-4g daily) or alternative agents 3
- If patient has structural lung disease (bronchiectasis, cystic fibrosis), two antipseudomonal agents are recommended regardless of other risk factors 2
- Base empiric therapy on local antibiograms whenever possible, as institutional resistance patterns vary significantly 2, 1
Transition to Oral Therapy and Duration
- Switch from IV to oral therapy when hemodynamically stable, clinically improving, able to ingest medications, and have normally functioning GI tract 2
- Minimum treatment duration is 5 days, with patient afebrile for 48-72 hours before discontinuation 2
- Inpatient observation while receiving oral therapy is not necessary once clinically stable 2