Community-Acquired Pneumonia Management (ATS 2025)

Algorithm Steps

1. ▶

   Start

   Suspected CAP

   Acute respiratory symptoms + new infiltrate on imaging

   1. ●

      Action

      Confirm Diagnosis

      Clinical presentation + imaging

      • Symptoms: Cough, fever, dyspnea, pleuritic chest pain
      • Physical: Crackles, bronchial breath sounds, egophony
      • Chest X-ray or CT showing infiltrate
      • Consider point-of-care ultrasound
      1. ◆

         Decision

         Assess Severity

         Determine site of care

         • CURB-65: Confusion, Urea >7, RR ≥30, BP <90/60, Age ≥65
         • 0-1: Outpatient, 2: Consider admission, 3-5: Inpatient/ICU
         • PSI: Alternative severity score
         • Clinical judgment for social/compliance factors
         1. ●

            Action

            Outpatient Treatment

            CURB-65 0-1, no comorbidities

            • Previously healthy, no risk factors:
            • Amoxicillin 1g PO TID x5 days, OR
            • Doxycycline 100mg PO BID x5 days, OR
            • Azithromycin 500mg day 1, then 250mg days 2-5
            • With comorbidities: Augmentin + macrolide OR respiratory FQ
            1. ●

               Action

               Duration of Therapy

               Shorter courses recommended

               • Minimum 5 days for uncomplicated CAP
               • Continue until afebrile ≥48h and clinically stable
               • Severe/complicated: 7 days minimum
               • Procalcitonin can guide de-escalation
               • Longer if: S. aureus bacteremia, lung abscess, empyema
               1. ◆

                  Decision

                  Consider Corticosteroids?

                  For severe CAP

                  • Suggested for severe CAP with high inflammatory markers
                  • Hydrocortisone 200mg/day or Methylprednisolone 40mg/day
                  • May reduce mortality and need for mechanical ventilation
                  • Avoid in influenza without bacterial coinfection
                  1. ◆

                     Decision

                     Clinical Response by 72h?

                     Assess for improvement

                     • Expect improvement in 48-72 hours
                     • Fever, WBC, respiratory status should trend down
                     • CRP/procalcitonin should decrease
                     1. ✓

                        Outcome

                        Improving - Continue Course

                        Switch to oral when stable

                        • IV to PO when: Tolerating PO, improving, no GI absorption issues
                        • Complete course as outpatient if appropriate
                        • Follow-up imaging at 6-8 weeks if indicated
                     2. ⚠

                        Warning

                        Not Improving

                        Evaluate for complications or alternative diagnoses

                        • Repeat imaging (CT chest)
                        • Consider bronchoscopy with BAL
                        • Rule out: Empyema, abscess, resistant organism
                        • Evaluate for non-infectious causes
                        • Expand antimicrobial coverage
         2. ●

            Action

            Inpatient Non-ICU

            CURB-65 2-3, not critically ill

            • Ampicillin-sulbactam 3g IV q6h + Azithromycin 500mg IV daily, OR
            • Ceftriaxone 1-2g IV daily + Azithromycin 500mg IV daily, OR
            • Respiratory fluoroquinolone monotherapy:
            • Levofloxacin 750mg IV/PO daily OR Moxifloxacin 400mg IV/PO daily
            1. ◆

               Decision

               Pseudomonas Risk Factors?

               Assess need for antipseudomonal coverage

               • Structural lung disease (bronchiectasis, CF)
               • Frequent antibiotics or prior Pseudomonas
               • Recent hospitalization/IV antibiotics
               1. ●

                  Action

                  Add Antipseudomonal Coverage

                  Use antipseudomonal beta-lactam

                  • Piperacillin-tazobactam 4.5g IV q6h, OR
                  • Cefepime 2g IV q8h, OR
                  • Meropenem 1g IV q8h
                  • PLUS respiratory fluoroquinolone or aminoglycoside
         3. ●

            Action

            ICU/Severe CAP

            CURB-65 4-5, major criteria, or shock/ventilation

            • Beta-lactam (Ceftriaxone 2g daily or Ampicillin-sulbactam 3g q6h)
            • PLUS Azithromycin 500mg daily OR Respiratory fluoroquinolone
            • Major criteria: Septic shock, mechanical ventilation
            • Minor criteria: RR ≥30, PaO2/FiO2 ≤250, multilobar, confusion, BUN ≥20, WBC <4000, platelets <100K, hypothermia, hypotension
            1. ◆

               Decision

               MRSA Risk Factors?

               Assess need for MRSA coverage

               • Prior MRSA infection/colonization
               • Recent hospitalization with IV antibiotics
               • Influenza with rapid cavitation
               • Gram stain with GPC in clusters
               1. ●

                  Action

                  Add MRSA Coverage

                  Vancomycin or Linezolid

                  • Vancomycin 15-20 mg/kg IV q8-12h (target trough 15-20), OR
                  • Linezolid 600mg IV/PO q12h (preferred for necrotizing)
                  • De-escalate if nasal swab negative and cultures negative at 48h