CAP, Hospitalized

[Am J Respir Crit Care Med 2019;200: e45-67, NICE guideline]

- Calculation of CRB-65, CURB-65 score, or Pneumonia Severity Index (PSI) is recommended to help determine severity, site of care and mortality risk.

- Investigations:

• CBC with differential, random glucose, electrolytes, creatinine, ALT
• Chest x-ray, PA and lateral
• Sputum Gram stain and C&S for patients with productive cough. For organism - specific recommendations, see Treatment of Culture-proven Pneumonia
• Blood cultures
• Nasopharyngeal (NP) swab/aspirate for respiratory virus PCR
• Sputum/NP sample for M. pneumoniae, C. pneumoniae, Legionella PCR.
• Legionella pneumophila urine antigen if severe CAP or epidemiological risk
• Consider mycobacterial/fungal culture if relevant history/travel, and PCP (P. jirovecii) in immunocompromised.
• Arterial blood gas on room air, or on baseline O₂ if patient receiving chronic oxygen

- Antibiotic therapy should be administered as soon as possible after the diagnosis is considered likely. This is especially important in the elderly.

Nonsevere

S. pneumoniae
H. influenzae
S. aureus
Group A Streptococci
Enterobacterales
Legionella spp
Chlamydia pneumoniae

Alternative

Severe

- See criteria below, or based on clinical judgement and guided by CRB-65 score 3 or 4 or CURB-65 3-5 or PSI score IV or V.

Severe CAP = 1 major criterion or 3 or more minor criteria:

Major criteria:

• septic shock requiring vasopressors
• respiratory failure requiring mechanical ventilation

Minor criteria:

• respiratory rate ≥ 30 breaths/minute
• PaO₂ /FiO₂ ratio ≤ 250
• multilobar infiltrates
• confusion/disorientation
• urea > 7mmol/L
• leukopenia (< 4 x 10⁹/L)
• thrombocytopenia (< 100 x 10⁹/L)
• hypothermia (< 36°C)
• hypotension requiring aggressive fluid resuscitation

- If deterioration or persistent respiratory/systemic symptoms, consider the following etiologies (depending on epidemiologic setting/risk factors):

• Viral pneumonia, including influenza, SARS-CoV-2, and Hantavirus
• Legionella spp
• Mycobacterium tuberculosis
• Chlamydophila psittaci
• Coxiella burnetti (Q fever)
• Francisella tularensis (tularemia)
• Endemic fungi (Histoplasma capsulatum, Coccidioides immitis, Cryptococcus neoformans, Blastomyces spp)
• Pneumocystis jirovecii

Corticosteroid therapy

- Routine use of corticosteroids in severe CAP not recommended, unless associated with refractory septic shock.

Antibiotic therapy

- The standard of care is with a β-lactam + macrolide. Combination therapy is associated with decreased mortality. 

S. pneumoniae
H. influenzae
S. aureus/MRSA
Group A Streptococci
Enterobacterales
Legionella spp
Chlamydia pneumoniae

Uncommon: 

P. aeruginosa

Consider viral:

Influenza

SARS-CoV-2

If MRSA suspected, add:

If P. aeruginosa suspected:

Ceftriaxone allergy