Pneumonia, Community-Acquired (CAP)

Criteria & Principles

Community-acquired pneumonia (CAP) symptom onset occurs prior to or within the first 2 days of hospital admission.
Pathogens to consider include: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarhallis and atypical pathogens (Legionella spp., Mycoplasma spp., Chlamydia pneumoniae). Staphylococcus aureus comprises <2% of CAP, but is more prevalent during influenza season.
Respiratory and blood cultures are recommended for the following patients: severe CAP, those with a personal history of MRSA or Pseudomonas aeruginosa, or patients previously hospitalized and treated with IV antibiotics within the last 90 days.
Additional diagnostic tests are appropriate for patients with severe CAP and/or risk factors: S. pneumoniae urine antigen, Legionella urine antigen, Legionella respiratory culture, Influenza PCR, respiratory viral panel.
For patients started on empiric coverage for MRSA, a negative nasal MRSA PCR or negative respiratory culture without MRSA at 48 hours have high negative predictive values. De-escalation of anti-MRSA coverage is recommended.

5-7 days

The majority of patients should be treated for 5 days, as most will achieve clinical stability within 48-72 hours.
Patients with pneumonia due to MRSA or Pseudomonas should be treated for 7 days (See HAP/VAP guideline)
High-dose (i.e. 500 mg) azithromycin achieves high concentrations in lung tissue that persist for several days. For most hospitalized patients, azithromycin can be stopped after three daily doses of 500 mg.

Patients should be assessed for risk factors (Table 1) and severity (Table 2) to determine empiric therapy choice.

NON-SEVERE

Outpatient community-acquired pneumonia (CAP):

Inpatient, non-severe, community-acquired pneumonia (CAP)

Empiric MRSA or Pseudomonas coverage is not necessary in patients with non-severe CAP without risk factors (see table 1).
Patients with non-severe CAP and prior hospitalization or IV antibiotics in the last 90 days should have blood and respiratory cultures collected. Therapy may then be escalated to include MRSA or Pseudomonas if cultures return positive.
*Recommend de-escalation of anti-MRSA and anti-pseudomonal agents at 48 hours if cultures are negative for these pathogens.
†Recommend PO formulations if patient can tolerate enteral feeding and oral medication, and if gastrointestinal absorption is intact.

Inpatient, severe, community-acquired pneumonia (CAP)

*Recommend de-escalation of anti-MRSA and anti-pseudomonal agents at 48 hours if cultures are negative for these pathogens.

Total duration of all CAP antibiotics: 5 days if clinically resolved for 72hrs
Renal dosing adjustments are required for ampicillin/sulbactam, amoxicillin/clavulanate, piperacillin/tazobactam, cefuroxime, and vancomycin.
We recommend AGAINST beta-lactam class switching. For example, avoid a switch from cephalosporin to a penicillin class oral agent for discharge.
We recommend AGAINST a class switch to oral fluoroquinolone for discharge. For example, avoid a switch from an intravenous beta-lactam to oral fluoroquinolone for discharge.

Metlay et al. Am J Respir Crit Care Med Vol 200, Iss 7, pp e45–e67, Oct 1, 2019