Q4 LONG ANSWER 10M ★ High-yield

Discuss the classification, aetiology, clinical features, severity assessment and management of pneumonia.

General Medicine · Final Professional

Definition and Classification

Pneumonia is acute inflammation of the lung parenchyma distal to the terminal bronchioles, with consolidation of alveolar spaces by inflammatory exudate.

Type	Definition	Organisms
Community-acquired (CAP)	Outside hospital, or within 48 h of admission	S. pneumoniae (commonest), H. influenzae, Mycoplasma, Chlamydophila, Legionella, viruses, Klebsiella (alcoholics, diabetics)
Hospital-acquired (HAP)	≥ 48 h after admission	Pseudomonas, Klebsiella, Acinetobacter, E. coli, MRSA — high multidrug resistance in Indian hospitals
Ventilator-associated (VAP)	≥ 48 h after intubation	As HAP
Aspiration	Aspiration of oropharyngeal/gastric contents	Anaerobes and mixed oral flora
Immunocompromised	HIV, transplant, chemotherapy	Pneumocystis, CMV, fungi, MYCOBACTERIA — always consider TB in India

Anatomical patterns: lobar (uniform lobar consolidation — classically pneumococcal), bronchopneumonia (patchy, bilateral, basal), and interstitial (viral, *Pneumocystis*).

Clinical Features

Typical (bacterial): abrupt high fever with RIGORS, productive cough with "RUSTY" SPUTUM in pneumococcal disease, PLEURITIC CHEST PAIN, breathlessness, and HERPES LABIALIS. Signs of CONSOLIDATION: reduced expansion, dull percussion, BRONCHIAL BREATHING, increased vocal resonance and whispering pectoriloquy, coarse crackles, pleural rub.

Atypical: insidious onset with prominent extrapulmonary features, few chest signs, and radiographic changes out of proportion to examination:

Organism	Distinctive features
Mycoplasma	Young adults, epidemics every 3–4 years; COLD AGGLUTININS with haemolysis; erythema multiforme and SJS; GUILLAIN–BARRÉ SYNDROME; bullous myringitis
Legionella	Contaminated water, air conditioning; HYPONATRAEMIA, deranged LFTs, diarrhoea, confusion; urinary antigen
Chlamydophila psittaci	Bird contact; splenomegaly, Horder's spots
Coxiella burnetii	Farm animal contact; hepatitis, endocarditis

In the elderly, presentation is frequently atypical — confusion, falls, decompensation or "off legs", often WITHOUT fever or cough.

Severity — Curb-65

CURB-65 — 1 point each

C = Confusion (new disorientation)

U = Urea > 7 mmol/L (~19 mg/dL)

R = Respiratory rate ≥ 30/min

B = Blood pressure — systolic < 90 or diastolic ≤ 60

65 = Age ≥ 65 years

Score	Mortality	Management
0–1	< 3%	Outpatient
2	~9%	Consider admission
3–5	15–40%	Admit; assess for ICU (4–5)

CRB-65 omits urea for primary care. Scores support but do not replace clinical judgement.

Investigations

CHEST X-RAY — consolidation with air bronchograms, effusion, cavitation, multilobar involvement. May be normal in early disease and dehydration; radiographic clearing lags clinical recovery by weeks
CBC (neutrophil leucocytosis; leucopenia indicates severe disease), urea and electrolytes (hyponatraemia in Legionella), LFT, CRP, glucose
Blood gas or oximetry; lactate in severe disease
BLOOD CULTURES and SPUTUM culture — before antibiotics in moderate and severe disease
Urinary antigens — pneumococcal and *Legionella*; respiratory viral PCR
HIV testing; sputum for AFB and CBNAAT where TB is possible — essential in India
Pleural aspiration for any significant effusion, to exclude empyema
CT and bronchoscopy for non-resolving pneumonia or suspected obstruction

Management

1. Antibiotics — the earlier the better. Give the first dose promptly (within 4 hours, and within 1 hour in septic shock) — delay is directly associated with increased mortality. Choice by severity, setting and local resistance:

Mild CAP: oral amoxicillin (or macrolide/doxycycline if atypical suspected)
Moderate: amoxicillin with a macrolide, or a respiratory fluoroquinolone
Severe: intravenous beta-lactam with a macrolide; add MRSA or *Pseudomonas* cover where risk factors exist
HAP/VAP: broad-spectrum cover strictly guided by local antibiograms — critical in Indian hospitals with carbapenem resistance
De-escalate on cultures; switch intravenous to oral on improvement; keep courses short (typically 5 days for CAP)

2. Supportive: oxygen (94–98%, or 88–92% in COPD), fluids, analgesia for pleuritic pain, early mobilisation, nutrition, thromboprophylaxis. Non-invasive or invasive ventilation for respiratory failure. Corticosteroids are now recommended in severe CAP on recent trial evidence.

3. Follow-up: repeat chest X-ray at about 6 weeks in smokers, those over 50 and those with persistent symptoms — to confirm resolution and exclude an underlying carcinoma. Frequently omitted, and a recognised cause of delayed cancer diagnosis.

Complications

Parapneumonic effusion and EMPYEMA, lung abscess, respiratory failure, sepsis and shock, ARDS, metastatic infection, atrial fibrillation and myocardial infarction, and non-resolving pneumonia — which must prompt consideration of TB, malignancy with obstruction, resistant organisms, empyema and non-infective mimics.

Prevention

Pneumococcal, influenza and COVID-19 vaccination; smoking cessation; oral and dental hygiene; management of dysphagia and reflux; and for HAP/VAP, head-up positioning, sedation minimisation, subglottic suction and hand hygiene.

DANGER / REMEMBER

A "pneumonia" that fails to resolve is tuberculosis or cancer until proved otherwise — particularly in India. Consolidation persisting beyond 4–6 weeks despite appropriate antibiotics requires sputum for AFB and CBNAAT, CT chest and bronchoscopy. Repeatedly changing antibiotics for a non-resolving infiltrate without pursuing these two diagnoses is a common and costly error.

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