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Q1: A 30-year-old presents with a dry cough, headache and fever; CXR shows patchy interstitial shadowing. Discuss the diagnosis and management. (2 min)
This is an atypical pneumonia — most likely Mycoplasma pneumoniae in a young adult (the single most common atypical in this age group). Distinguishing features: insidious onset, dry non-productive cough, prominent headache and myalgia, low-grade fever, and a CXR that often looks worse than the patient. Ask about school/college outbreaks and extrapulmonary features (erythema multiforme, cold-agglutinin haemolytic anaemia, Guillain-Barre). Cold agglutinins (IgM anti-I) and a four-fold rise in Mycoplasma IgG support the diagnosis; PCR is available. Treat with a macrolide (clarithromycin 500 mg twice daily or azithromycin 500 mg on day 1 then 250 mg daily) or doxycycline 100 mg twice daily — beta-lactams are ineffective because Mycoplasma lacks a cell wall. Duration follows clinical stability, minimum 5 days.
Q2: How do you assess severity and decide the site of care in CAP? (3 min)
Use CURB-65 — Confusion, Urea over 7 mmol/L, RR 30 or more, BP systolic under 90 or diastolic 60 or less, age 65 or more; one point each, maximum 5. Lim 2003 30-day mortality: 0.7, 3.2, 3, 17, 41.5 and 57 percent at scores 0–5. NICE CG191: consider home at 0 or 1, hospital at 2 or more, intensive-care assessment at 3 or more (bands: low under 3 percent, intermediate 3–15 percent, high over 15 percent) — always with clinical judgement. Where urea is unavailable use CRB-65. IDSA/ATS severe CAP: one major (vasopressor septic shock or mechanical ventilation) or three or more of nine minor (RR 30 or more, PaO2/FiO2 250 or less, multilobar, confusion, BUN 20 mg/dL or more, WBC under 4,000/µL, platelets under 100,000/µL, core temperature under 36 °C, hypotension needing aggressive fluids). ATS/IDSA 2019 prefers PSI over CURB-65 to decide hospitalisation.
Q3: A 55-year-old alcoholic presents with high fever and thick red-currant-jelly sputum; CXR shows right upper-lobe consolidation with a bulging fissure. Discuss. (2 min)
Classic Klebsiella pneumoniae (Friedlander) pneumonia. Risk factors: alcoholism, diabetes, chronic lung disease, malnutrition. The thick red-currant-jelly sputum reflects the organism's thick capsule and haemorrhagic necrosis; upper-lobe predilection with a bulging fissure (from volume expansion of consolidated lung); it cavitates readily and may progress to lung abscess or empyema. It is a Gram-negative bacillus with a prominent polysaccharide capsule. Treat empirically with a third-generation cephalosporin (ceftriaxone) plus a macrolide until sensitivities return, broadening to a carbapenem for hypervirulent or ESBL-producing strains. Be alert to bacteraemia, abscess formation and metastatic infection (endophthalmitis, liver abscess in the hypervirulent K1/K2 capsular type).
Q4: Discuss the complications of CAP and how you would manage a parapneumonic effusion. (2 min)
Local: parapneumonic effusion, empyema, lung abscess, necrotising pneumonia, pneumatocele, bronchopleural fistula. Systemic: sepsis and septic shock, ARDS, acute kidney injury, new atrial fibrillation (elderly), hyponatraemia (SIADH or adrenal), and metastatic infection (endocarditis, meningitis, arthritis). For a parapneumonic effusion, first aspirate and analyse (pH, glucose, LDH, Gram stain and culture); all parapneumonic effusions should be sampled. Insert a chest tube if size is half a hemithorax or more, loculated, pH under 7.20 (or glucose under 60 mg/dL), Gram stain or culture positive, or purulent. Drainage options include therapeutic thoracentesis, tube thoracostomy, intrapleural fibrinolytics (routine use remains controversial), thoracoscopy, or thoracotomy with decortication.