What is the initial management approach for a patient presenting with pneumonia, considering factors such as age, medical history, and severity of symptoms?

Initial Management of Community-Acquired Pneumonia

For hospitalized patients with non-severe community-acquired pneumonia, initiate combination therapy with a β-lactam (ceftriaxone 1-2g daily or ampicillin-sulbactam 1.5-3g every 6 hours) plus a macrolide (azithromycin 500mg daily or clarithromycin 500mg twice daily) immediately upon diagnosis, with the first dose administered in the emergency department. 1, 2

Outpatient Management

Previously healthy patients without comorbidities:

• First-line: Amoxicillin 1g orally three times daily for 5-7 days 2, 3
• Alternative: Doxycycline 100mg twice daily (with initial 200mg loading dose) 2
• Macrolide monotherapy (azithromycin 500mg Day 1, then 250mg Days 2-5) is appropriate for patients under 40 years when atypical pathogens are suspected 2, 4

Patients with comorbidities or recent antibiotic use (within 90 days):

• Combination therapy: Amoxicillin-clavulanate 875mg/125mg twice daily PLUS azithromycin 500mg daily 2, 3
• Alternative monotherapy: Respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1, 2

Critical caveat: Patients who received antibiotics from one class within 90 days must receive a different antibiotic class due to resistance risk 2. Fluoroquinolones should be reserved for patients with β-lactam allergies or specific indications to prevent resistance development 2.

Hospitalized Non-ICU Patients

Standard regimen (no risk factors for resistant organisms):

• β-lactam PLUS macrolide: Ceftriaxone 1-2g every 24 hours OR ampicillin-sulbactam 1.5-3g every 6 hours PLUS azithromycin 500mg daily OR clarithromycin 500mg twice daily 1, 2, 5
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1, 2

Timing is critical: The first antibiotic dose must be administered in the emergency department; delays beyond 8 hours increase 30-day mortality by 20-30% 3. This represents a strong recommendation based on mortality data 2.

Transition to oral therapy when the patient meets ALL stability criteria: hemodynamically stable, clinically improving, afebrile for 48-72 hours, decreasing white blood cell count, and able to take oral medications 3. This typically occurs by hospital day 2-3 3.

Severe CAP/ICU Patients

Without Pseudomonas risk factors:

• β-lactam PLUS macrolide: Ceftriaxone 1-2g every 24 hours OR cefotaxime 1-2g every 8 hours PLUS azithromycin 500mg daily 1, 2
• Alternative: β-lactam PLUS respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1, 2

With Pseudomonas risk factors (structural lung disease, recent hospitalization, recent broad-spectrum antibiotics):

• Antipseudomonal β-lactam (piperacillin-tazobactam 4.5g every 6 hours, cefepime 2g every 8 hours, or meropenem 1g every 8 hours) PLUS ciprofloxacin 400mg IV every 8 hours OR levofloxacin 750mg daily 1, 2
• Alternative: Antipseudomonal β-lactam PLUS aminoglycoside (gentamicin or tobramycin) PLUS azithromycin 1, 2

MRSA Coverage

Add vancomycin 15mg/kg every 12 hours (adjust based on levels) OR linezolid 600mg every 12 hours when:

• Prior MRSA infection documented 1, 2
• Recent hospitalization with parenteral antibiotics 1
• Obtain nasal PCR and cultures to allow de-escalation within 48-72 hours if negative 1

Important distinction: For patients WITHOUT MRSA risk factors, obtain cultures but withhold empiric MRSA coverage unless rapid nasal PCR is positive or cultures return positive 1.

Duration of Therapy

Minimum 5 days AND patient must be afebrile for 48-72 hours with no more than one sign of clinical instability before discontinuing 2, 3. Standard duration is 5-7 days for uncomplicated cases 3. Extend to 14-21 days for specific pathogens (Legionella, Staphylococcus aureus, Gram-negative enteric bacilli) 2.

Severity Assessment

Use CURB-65 score to guide site-of-care decisions: 3

• Confusion (new onset)
• Urea >7 mmol/L (BUN >19 mg/dL)
• Respiratory rate ≥30 breaths/minute
• Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg)
• Age ≥65 years

Score 0-1: Outpatient treatment appropriate 3 Score ≥2: Consider hospitalization 3 Score ≥3: Severe pneumonia, high mortality risk, requires hospitalization 6

Diagnostic Testing

All patients require:

• Chest radiograph (posteroanterior and lateral) to confirm diagnosis 6, 3
• Pulse oximetry for oxygenation assessment 3
• Complete blood count, basic metabolic panel (including urea/creatinine for CURB-65 calculation) 6

Hospitalized patients require:

• Blood cultures (two sets from separate sites before antibiotics) 3
• COVID-19 and influenza testing when circulating in community 3, 5
• Sputum Gram stain and culture if drug-resistant organisms suspected 6

Critical pitfall: Never delay antibiotic administration for diagnostic testing 6. Empiric therapy should be initiated regardless of initial procalcitonin level 1.

Common Pitfalls to Avoid

Inadequate atypical coverage: Ensure coverage for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila, as clinical success is significantly higher when atypical antibiotics are used for Legionella 2. This is why combination therapy with a macrolide is preferred over β-lactam monotherapy 1, 2.

Fluoroquinolone overuse: Reserve for patients with documented β-lactam allergies or specific indications 2. The FDA has issued warnings about adverse events including tendon rupture, peripheral neuropathy, and CNS effects 2, 4.

Macrolide resistance: S. pneumoniae resistance to macrolides ranges 30-40% and often co-exists with β-lactam resistance 2. This is why combination therapy (β-lactam PLUS macrolide) is superior to macrolide monotherapy in hospitalized patients 1, 2.

Delayed antibiotic administration: Studies consistently show that inappropriate or delayed initial antibiotic therapy increases mortality 1, 7, 8. Subsequent modification of inadequate therapy does not remedy the impact of the initial choice 7, 8.

Follow-Up

Clinical review at 6 weeks with repeat chest radiograph for patients with persistent symptoms, physical signs, or high risk for underlying malignancy (especially smokers over 50 years) 1, 6. Chest radiograph need not be repeated prior to discharge in patients with satisfactory clinical recovery 1, 6.