MBBS SAQ · Infectious Diseases / Respiratory
Severe community-acquired pneumonia — recognition, severity and empirical therapy
A final-prof / NEET-PG SAQ on severe CAP — ABCDE + CURB-65 scoring (this patient scores 5 → severe/ICU), Sepsis-6 bundle, oxygen targets, and empirical IV beta-lactam + macrolide within 4 hours, with escalation to MRSA cover if risk.
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Question
A 68-year-old man with type 2 diabetes presents with 3 days of fever, productive cough and dyspnoea. On examination he is confused, RR 32, SpO2 90% on air, BP 86/54, and right-base crackles with dullness. CXR shows right lower-lobe consolidation; urea 9.2 mmol/L, WBC 18 x10^9/L. Outline your assessment, severity stratification and immediate management.
Model answer
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Diagnosis: severe community-acquired pneumonia with sepsis. The consolidation plus the systemic inflammatory response (confusion, tachypnoea, hypotension, leukocytosis) establish CAP with septic response; the diabetes is a comorbidity.[1][2]
Immediate assessment — ABCDE. Airway patent; Breathing — high-flow oxygen to target SpO2 94–98% (88–92% only if chronic CO2 retention); Circulation — IV access, fluids for hypotension; Disability — confusion (GCS, glucose, infection marker); Exposure — full sets, sepsis screen.[1]
Severity stratification — CURB-65 = 5 (severe).[3]
- Confusion (1) + Urea over 7 (1) + RR over 30 (1) + BP under 90 systolic (1) + age over 65 (1) = 5.
- A score of 3–5 mandates hospital admission with ICU consideration; this patient meets ICU criteria (also fulfils ATS/IDSA severe-CAP: hypotension needing aggressive fluids).[1]
Sepsis-6 within the first hour.[1]
- Cultures (blood, sputum) + lactate + urine output (catheter); give broad-spectrum antibiotics; give balanced crystalloid 30 mL/kg; start noradrenaline if fluid-refractory shock.
Empirical antibiotics within 4 hours (severe/ICU).[1][2]
- IV ceftriaxone + azithromycin (beta-lactam + macrolide) — covers typical (S. pneumoniae, H. influenzae) AND atypical organisms.
- Add MRSA cover (vancomycin/linezolid) and antipseudomonal cover if risk factors (post-influenza, healthcare exposure, structural lung disease).
- In India apply the local antibiogram / ICMR guidance.[1]
Targeted investigations. Blood cultures, sputum Gram stain/culture, urinary antigens (pneumococcal + Legionella given severity), viral PCR (influenza, COVID-19), ABG/lactate, CRP. Reassess at 48–72 h for response; consider steroids in severe CAP with septic shock.[1]
Common errors
- Under-grading severity — not applying CURB-65, or treating a score-5 patient on a general ward.
- Not covering atypicals — beta-lactam alone misses Mycoplasma/Legionella.
- Delaying antibiotics for investigations — cultures first, but antibiotics within 4 h (1 h if septic shock).
- Missing a complication — not looking for parapneumonic effusion/empyema or underlying cause; not considering TB/PE/COVID-19.
- Oxygen overshoot — 100% O2 in a CO2-retainer; use 88–92% target in COPD.
Examiner notes
- The exam wants the structured approach: ABCDE → severity score (CURB-65 reproduced with components) → Sepsis-6 → empirical regimen with drug, dose and rationale → escalation and disposition.
- State the antibiotic timing (within 4 h) and duration (5–7 d once improving) to score full marks.
- A strong candidate mentions vaccination on recovery (pneumococcal, influenza, COVID-19) and follow-up CXR at 6–8 weeks (smoker over 50 → exclude malignancy).[1][2]
References3ShowHide
- [1]Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-Acquired Pneumonia. ATS/IDSA 2019. Am J Respir Crit Care Med, 2019.PMID 31573350
- [2]Prina E, Ranzani OT, Torres A. Community-acquired pneumonia. Lancet, 2015.PMID 26277247
- [3]Lim WS, et al. Defining community acquired pneumonia severity on presentation to hospital (CURB-65). Thorax, 2003.PMID 12728155