Management of Community-Acquired Pneumonia: Admission, Diagnostics, Treatment, and Discharge
When to Admit a Pneumonia Patient
Hospitalization is required when patients have multiple risk factors for mortality or complications, guided by objective scoring systems but ultimately based on clinical judgment incorporating physiologic derangements, comorbidities, and social factors. 1
Risk Stratification Tools
Use CURB-65 or PORT Prediction Rule to guide admission decisions:
CURB-65 score ≥2 warrants hospitalization or intensive home care 1
- Confusion
- Urea (BUN) >7.0 mM (>19.1 mg/dL)
- Respiratory rate ≥30/min
- Blood pressure: systolic <90 or diastolic ≤60 mm Hg
- Age ≥65 years
PORT Prediction Rule Classes:
Specific Clinical Criteria for Admission
Admit patients with any of these high-risk features: 1
Vital Sign Abnormalities:
- Respiratory rate ≥30 breaths/min
- Systolic BP <90 mm Hg or diastolic BP ≤60 mm Hg
- Heart rate ≥125/min
- Temperature <35°C or ≥40°C
- Altered mental status or confusion
Laboratory/Radiographic Findings:
- PaO₂ <60 mm Hg or O₂ saturation <90% on room air 1
- PaCO₂ ≥50 mm Hg on room air 1
- WBC <4 × 10⁹/L or absolute neutrophil count <1 × 10⁹/L 1
- Serum creatinine ≥1.2 mg/dL or BUN ≥20 mg/dL 1
- Hematocrit <30% or hemoglobin <9 g/dL 1
- Arterial pH <7.35 1
- Multilobar involvement, cavitation, or pleural effusion on chest X-ray 1
- Evidence of sepsis, metabolic acidosis, or coagulopathy 1
Patient Factors:
- Age >65 years 1
- Significant comorbidities: COPD, malignancy, diabetes, chronic renal failure, CHF, chronic liver disease, cerebrovascular disease, immunosuppression 1
- Hospitalization within past year 1
- Inability to take oral medications 1
- Lack of reliable caregiver or unsafe home environment 1
Important caveat: Even when objective criteria suggest low risk, clinical judgment should prevail—if the patient appears severely ill, admit for 24-48 hour observation 1
ICU Admission Criteria
Direct ICU admission is required for: 1
Major Criteria (presence of ONE requires ICU):
- Need for mechanical ventilation
- Septic shock requiring vasopressors
Minor Criteria (presence of THREE requires ICU):
- Respiratory rate >30/min
- PaO₂/FiO₂ ratio <250
- Multilobar infiltrates
- Confusion
- BUN ≥20 mg/dL
- Leukopenia (WBC <4,000)
- Thrombocytopenia (platelets <100,000)
- Hypothermia (core temperature <36°C)
- Hypotension requiring aggressive fluid resuscitation
Alternative BTS criteria (≥2 of 4 indicates severe illness, consider ICU): 1
- Respiratory rate >30/min
- Diastolic BP <60 mm Hg
- BUN >7.0 mM (>19.1 mg/dL)
- Confusion
Diagnostic Workup
Outpatient Diagnostics
For patients managed as outpatients: 1
- Chest radiograph (mandatory) to confirm pneumonia
- Sputum Gram stain and culture only if drug-resistant pathogen or atypical organism suspected
- Pulse oximetry if chronic cardiopulmonary disease present
- No routine blood work required for uncomplicated cases
Inpatient Diagnostics
For all hospitalized patients, obtain: 1
Imaging:
- Chest radiograph (PA and lateral if possible)
Laboratory Tests:
- Complete blood count with differential
- Basic metabolic panel (electrolytes, BUN, creatinine, glucose)
- Liver function tests
- Pulse oximetry (all patients)
- Arterial blood gas if severe illness, chronic lung disease, or oxygen saturation concerns 1
Microbiological Studies:
- Two sets of blood cultures before antibiotics (yield ~11%, identifies bacteremia and resistant pathogens) 1
- Sputum Gram stain and culture if drug-resistant pathogen or unusual organism suspected; Gram stain should use highly sensitive criteria to identify unexpected organisms (e.g., S. aureus, gram-negatives) that require broader coverage 1
- Legionella urinary antigen for severe CAP 1
- Thoracentesis for any pleural effusion ≥10 mm on lateral decubitus film or any loculated effusion 1
For severe CAP requiring ICU admission:
- Consider bronchoscopy for lower respiratory tract sampling in selected patients, though benefit not definitively proven 1
- Aggressive etiologic diagnosis attempts 1
Do NOT routinely obtain:
- Serologic testing 1
- Sputum studies in patients responding well to empiric therapy
Treatment
Timing of Antibiotics
Administer first antibiotic dose within 8 hours of hospital arrival; for ED admissions, give first dose while still in ED 1
Empiric Antibiotic Regimens
Outpatient Treatment (Non-ICU, Low Risk)
Previously healthy, no recent antibiotics: 1
- Macrolide monotherapy: Azithromycin 500 mg Day 1, then 250 mg daily Days 2-5 2 OR erythromycin or clarithromycin
- Alternative: Doxycycline
Comorbidities or recent antibiotic use (risk factors for DRSP, gram-negatives): 1
- Respiratory fluoroquinolone (levofloxacin, moxifloxacin) alone, OR
- β-lactam PLUS macrolide:
- Oral β-lactams: High-dose amoxicillin, amoxicillin-clavulanate, cefpodoxime, or cefuroxime 1
- PLUS azithromycin or clarithromycin
Hospitalized, Non-ICU Patients
Standard regimen: 1
- β-lactam (IV) PLUS macrolide (IV or PO):
- Ceftriaxone, cefotaxime, or ampicillin-sulbactam
- PLUS azithromycin or clarithromycin
- Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin, moxifloxacin)
Both regimens are therapeutically equivalent for inpatients 1
ICU Patients (Severe CAP)
Standard severe CAP regimen: 1
- β-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) PLUS either:
- Azithromycin (Level II evidence), OR
- Respiratory fluoroquinolone (Level I evidence)
Do NOT use fluoroquinolone monotherapy in ICU patients 1
For Pseudomonas risk factors (structural lung disease, recent broad-spectrum antibiotics, recent hospitalization): 1
- Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem)
- PLUS ciprofloxacin or levofloxacin 750 mg, OR
- Antipseudomonal β-lactam PLUS aminoglycoside PLUS azithromycin or fluoroquinolone
For suspected MRSA: 1
- Add vancomycin or linezolid
Penicillin-allergic patients:
- Substitute aztreonam for β-lactam 1
- Use respiratory fluoroquinolone plus aztreonam
Duration of Therapy
Minimum 5 days of treatment 1
- Patient must be afebrile for 48-72 hours
- No more than 1 sign of clinical instability before discontinuation 1
Longer duration needed if:
- Initial therapy not active against identified pathogen
- Extrapulmonary complications (meningitis, endocarditis) 1
Switching to Oral Therapy
Switch from IV to oral when: 1
- Hemodynamically stable
- Clinically improving
- Able to ingest medications
- Normally functioning GI tract
Discharge as soon as clinically stable; inpatient observation on oral therapy unnecessary 1
Discharge Criteria
Patients may be discharged when ALL of the following are met: 1
Clinical Stability Criteria
- Temperature ≤37.8°C (100°F)
- Heart rate ≤100 beats/min
- Respiratory rate ≤24 breaths/min
- Systolic BP ≥90 mm Hg
- Oxygen saturation ≥90% on room air (or baseline for COPD patients)
- Able to maintain oral intake
- Normal mental status
Additional Discharge Requirements
- No other active medical problems requiring hospitalization 1
- Safe environment for continued care 1
- Reliable caregiver if needed 1
Follow-Up Planning
At discharge: 1
- Provide patient education materials
- Arrange clinical follow-up at 6 weeks with primary care or pulmonary clinic 1
Repeat chest radiograph at 6 weeks for: 1
- Persistent symptoms or physical signs
- Smokers and patients >50 years (higher malignancy risk)
- Any patient not making satisfactory clinical recovery
Do NOT repeat chest X-ray before discharge if satisfactory clinical recovery 1
Common Pitfalls
Avoid these errors: 1
- Over-relying on scoring systems without clinical judgment—30% of "low-risk" patients still require admission for valid reasons
- Underestimating severity in young patients with severe physiologic derangements (PORT heavily weights age)
- Delaying ICU transfer—delayed recognition of respiratory failure or septic shock increases mortality
- Using fluoroquinolone monotherapy in ICU patients—insufficient evidence for severe CAP
- Discharging patients before achieving clinical stability criteria
- Failing to arrange appropriate follow-up for high-risk patients (smokers, elderly)