Community-Acquired Pneumonia (CAP) in Adults
Empiric antibiotic therapy should be initiated when CAP is clinically suspected and radiographically confirmed, regardless of initial procalcitonin level [1]. Empiric regimens should be selected by site of care and by risk factors for MRSA or Pseudomonas aeruginosa [1].
Diagnostic Workup and Testing Strategy
Empiric antibiotics should be started only after clinical suspicion and radiographic confirmation of CAP [1].
Lower-respiratory tract Gram stain and culture should be obtained in hospitalized patients when clinically indicated for pathogen targeting or severity [1].
Blood cultures should be avoided in outpatients [1].
Blood cultures should be suggested against in hospitalized non-severe CAP [1].
Pretreatment blood cultures should be obtained in hospitalized severe CAP or when empiric MRSA or P. aeruginosa therapy is being used, or when recent hospitalization plus parenteral antibiotics in the last 90 days is present [1].
Urinary antigen testing should not be performed routinely for pneumococcal antigen, except in severe CAP [1].
Urinary antigen testing should not be performed routinely for Legionella antigen, except with epidemiologic factors (for example, outbreak association or recent travel) or in severe CAP [1].
Site-of-Care Determination
Hospitalization need should be determined using clinical judgment plus the Pneumonia Severity Index (PSI) preferentially over CURB-65 [1].
Severe CAP should be defined by the 2007 ATS/IDSA criteria, using either 1 major criterion or ≥3 minor criteria [1].
Medication Selection Algorithm
Outpatient CAP without MRSA or P. aeruginosa risk factors
Recommended empiric options include:
- Amoxicillin [1]
- Doxycycline [1]
- A macrolide only when local pneumococcal resistance is <25% [1]
Outpatient CAP with comorbidities (or equivalent poor-outcome risk)
Recommended empiric options include:
- Combination therapy: amoxicillin/clavulanate or a cephalosporin plus a macrolide, or plus doxycycline [1]
- Monotherapy with a respiratory fluoroquinolone [1]
Inpatient CAP without MRSA or P. aeruginosa risk factors
Recommended empiric options include:
- A beta-lactam plus a macrolide [1]
- A beta-lactam plus a respiratory fluoroquinolone [1]
- Monotherapy with a respiratory fluoroquinolone [1]
Inpatient CAP with risk factors for MRSA or P. aeruginosa
MRSA risk factors should include prior respiratory isolation of MRSA or prior hospitalization plus receipt of parenteral antibiotics in the last 90 days [1].
P. aeruginosa risk factors should include prior respiratory isolation of P. aeruginosa or prior hospitalization plus receipt of parenteral antibiotics in the last 90 days [1].
Recommended empiric approach should include:
- Addition of MRSA coverage with cultures and nasal PCR to allow de-escalation or confirmation of need [1]
- Addition of P. aeruginosa coverage with cultures to allow de-escalation or confirmation of need [1]
Monotherapy Versus Combination Therapy
Outpatient CAP without comorbidities or MRSA/P. aeruginosa risk factors should use amoxicillin or doxycycline or a macrolide only when local pneumococcal resistance is <25% [1].
Outpatient CAP with comorbidities should use:
- Beta-lactam plus macrolide, or beta-lactam plus doxycycline [1]
- Respiratory fluoroquinolone monotherapy [1]
Inpatient CAP without MRSA/P. aeruginosa risk factors should use:
- Beta-lactam plus macrolide or beta-lactam plus respiratory fluoroquinolone or respiratory fluoroquinolone monotherapy [1].
Treatment Initiation Thresholds and Antibiotic Duration
Antibiotic therapy should be initiated in adults with clinically suspected and radiographically confirmed CAP regardless of initial procalcitonin level [1].
Antibiotic duration should be guided by clinical stability and should continue until clinical stability is achieved [1].
Total duration should be no less than 5 days [1].
When switching from parenteral to oral therapy, the same agent or the same drug class should be used [1].
MRSA or P. aeruginosa CAP should be treated for 7 days [1].
Early discontinuation at 48–72 hours may be considered only in the setting of influenza positivity, no evidence of a bacterial pathogen (including low procalcitonin), and early clinical stability [1].
Influenza-Positive CAP Antiviral Use
Antiviral therapy should be included for adults with CAP who test positive for influenza in the inpatient setting, independent of duration of illness before diagnosis [1].
Antiviral therapy should be suggested for adults with CAP who test positive for influenza in the outpatient setting, independent of duration of illness before diagnosis [1].