Pneumonia in Children

Pneumonia is the single largest infectious cause of death in under-5 children worldwide. For NEET PG the highest-yield zones are the WHO/IMNCI fast-breathing cut-offs, the severity classification, age-wise organism patterns, and empirical antibiotic choice. This note is built to let you answer any clinical vignette or one-liner on those.

Definition & classification

Pneumonia is acute inflammation of the lung parenchyma (alveoli and terminal airways), usually infective, presenting with cough/respiratory distress plus radiological or clinical signs of parenchymal involvement. In children the diagnosis is largely clinical; the chest X-ray is confirmatory, not screening.

Classification can be approached in several ways:

Basis	Categories
Anatomical	Lobar pneumonia, bronchopneumonia (lobular), interstitial pneumonia, necrotising pneumonia
Setting	Community-acquired (CAP), hospital-acquired/ventilator-associated (HAP/VAP)
Aetiology	Bacterial, viral, atypical, fungal, aspiration, chemical
Severity (WHO/IMNCI)	No pneumonia → Pneumonia → Severe pneumonia (old "very severe" now merged)
Radiological	Typical (lobar, consolidation) vs atypical (diffuse, interstitial, perihilar)

High-yield: In a child, fast breathing is the most sensitive single sign of pneumonia, and lower chest indrawing (subcostal recession) is the hallmark of severe pneumonia.

WHO / IMNCI respiratory rate thresholds

This is the most repeatedly tested table in paediatric respiratory medicine. Fast breathing is defined age-specifically because normal respiratory rate falls as the child grows.

Age group	Fast breathing cut-off (breaths/min)
< 2 months (young infant)	≥ 60
2–12 months	≥ 50
12 months – 5 years	≥ 40
≥ 5 years	≥ 30 (adult-type threshold)

High-yield mnemonic: "60-50-40" for the three under-5 bands. Remember the rates fall by 10 as the age band rises.

Respiratory rate must be counted for a full 60 seconds in a calm child. If the first count is high, repeat to confirm before classifying.

IMNCI / WHO severity classification (2014 revision)

WHO simplified the classification in 2014, merging the old "very severe pneumonia" into "severe pneumonia" and allowing oral amoxicillin for non-severe pneumonia.

Stepwise approach (child 2 months–5 years presenting with cough/difficult breathing):

Check danger signs → check chest indrawing → check fast breathing → classify

1. Severe pneumonia — cough or difficult breathing PLUS any of:
   • Central cyanosis or SpO₂ < 90%
   • Lower chest wall indrawing
   • General danger signs: not able to drink/feed, persistent vomiting, convulsions, lethargy/unconsciousness, stridor in a calm child → Refer urgently, give first dose of injectable antibiotic, oxygen.
2. Pneumonia — fast breathing and/or chest indrawing but no danger sign → treat at home with oral amoxicillin.
3. No pneumonia (cough or cold) — no fast breathing, no indrawing → home care, no antibiotic, review in 3 days.

High-yield: Under the 2014 WHO update, chest indrawing alone (without danger signs) is now classified as "pneumonia" treatable with oral amoxicillin at home, NOT automatically severe. This is a favourite "recently changed guideline" MCQ.

For the young infant (< 2 months), the algorithm differs: ANY fast breathing (≥60) or severe chest indrawing is classified as "severe pneumonia / very severe disease" and needs referral — neonates are never managed at home.

Age-wise aetiology

Organism patterns shift predictably with age — the classic distractor-rich MCQ. Overall, viruses dominate in under-5s (RSV is the commonest cause of pneumonia in infants), while bacteria cause more severe disease.

Age	Likely organisms (most characteristic)
Birth–3 weeks (neonate)	Group B Streptococcus, E. coli/Gram-negatives, Listeria monocytogenes (vertical transmission)
3 weeks–3 months	Chlamydia trachomatis (afebrile "staccato" pneumonia, conjunctivitis, eosinophilia), RSV, S. pneumoniae, Bordetella pertussis
4 months–4 years	RSV / respiratory viruses (commonest overall), Streptococcus pneumoniae (commonest bacterial), H. influenzae, S. aureus
5–15 years (school-age)	Mycoplasma pneumoniae and Chlamydophila pneumoniae (atypical "walking pneumonia"), S. pneumoniae

High-yield triad to memorise:

• Neonate → afebrile pneumonia + conjunctivitis = Chlamydia trachomatis
• Toddler → commonest bacterial = Strep pneumoniae
• School-age → Mycoplasma (walking pneumonia, bullous myringitis, cold agglutinins)

Special situations:

• Staphylococcus aureus → rapidly progressive, pneumatocoeles, empyema, pneumothorax; suspect after measles or in infants.
• Post-influenza / post-measles → secondary bacterial (S. aureus, S. pneumoniae).
• Recurrent same-lobe pneumonia → think structural (sequestration, foreign body, bronchiectasis).
• Recurrent different-lobe → think systemic (immunodeficiency, cystic fibrosis, aspiration/GERD, ciliary dyskinesia).

Pathophysiology

Pathogens reach the lower respiratory tract chiefly by micro-aspiration of nasopharyngeal flora; haematogenous spread (e.g. S. aureus) is less common. Once alveolar invasion occurs there is exudation, neutrophil/macrophage influx and consolidation (typical lobar) or a more diffuse interstitial/peribronchial inflammation (viral/atypical). The four classic lobar stages — congestion → red hepatisation → grey hepatisation → resolution — are textbook though rarely fully seen in treated children. Consolidation impairs ventilation while perfusion continues, producing V/Q mismatch and intrapulmonary shunt → hypoxaemia, the basis for fast breathing and recession (compensatory increase in respiratory drive and work of breathing).

Clinical features

• General: fever, cough, poor feeding, lethargy, irritability.
• Respiratory: tachypnoea (earliest/most sensitive), grunting, nasal flaring, chest indrawing (subcostal/intercostal), head nodding in infants, cyanosis.
• Auscultation: localised crepitations, bronchial breathing, reduced air entry, dullness on percussion (consolidation/effusion).
• Atypical/Mycoplasma: gradual onset, low-grade fever, dry hacking cough, headache, malaise, examination often disproportionately normal ("walking pneumonia"), extrapulmonary features (haemolytic anaemia, erythema multiforme/Stevens-Johnson, Guillain-Barré, bullous myringitis).
• Pointers to complication: persistent high fever despite 48–72 h antibiotics, worsening distress, dullness with absent breath sounds (effusion/empyema), sudden deterioration (pneumothorax).

High-yield: Grunting and chest indrawing in an infant indicate significant respiratory compromise (severe pneumonia) and mandate oxygen + referral.

Diagnosis & investigation of choice

In an outpatient/IMNCI setting the diagnosis is purely clinical — no investigation is needed to start treatment of non-severe pneumonia.

• Chest X-ray (PA view) — investigation of choice to confirm and to detect complications (effusion, abscess, pneumatocoele). NOT routinely indicated in mild outpatient CAP. Patterns:
  • Lobar consolidation → typically pyogenic (pneumococcus).
  • Diffuse/interstitial/perihilar streaking → viral or atypical.
  • Pneumatocoeles/empyema/pneumothorax → S. aureus.
  • Round pneumonia → often pneumococcal in young children.
• SpO₂ by pulse oximetry — essential; < 90% defines severe disease and the need for oxygen.
• Blood cultures — positive in <10–15%; reserve for severe/hospitalised cases.
• CBC, CRP/procalcitonin — support bacterial vs viral but not definitive; high procalcitonin favours bacterial.
• Cold agglutinins / Mycoplasma IgM / PCR — for suspected atypical pneumonia in school-age children.
• Pleural fluid analysis (if effusion) — guides empyema management; pH < 7.2, glucose < 40 mg/dL, LDH high, pus → complicated effusion needing drainage.
• Nasopharyngeal viral PCR / RSV antigen — for viral confirmation/cohorting.

High-yield: Routine CXR is NOT recommended for uncomplicated outpatient CAP (BTS/WHO). Order it when severe, hospitalised, failing therapy, or suspecting complications.

Management & drug of choice

Management follows severity stratification.

Outpatient (non-severe "pneumonia"):

• Oral amoxicillin is the drug of choice — WHO now recommends high-dose oral amoxicillin (≈ 80–90 mg/kg/day in 2 divided doses for 5 days) as superior to older amoxicillin and to cotrimoxazole, covering penicillin-intermediate pneumococcus.
• Supportive: antipyretics (paracetamol), fluids, continue feeding/breastfeeding, no cough suppressants.

Inpatient (severe pneumonia):

• Injectable ampicillin (or penicillin) + gentamicin is the WHO first-line for severe pneumonia requiring referral; ceftriaxone is second-line/where resistance suspected.
• Oxygen for SpO₂ < 90% / central cyanosis / severe indrawing / inability to feed.
• Add cloxacillin/vancomycin if staphylococcal pneumonia suspected (pneumatocoele, empyema, rapid deterioration, post-measles).

Atypical (school-age, suspected Mycoplasma/Chlamydophila):

• Macrolide — azithromycin / clarithromycin / erythromycin is the drug of choice. Beta-lactams are ineffective (no cell wall in Mycoplasma).

Neonatal pneumonia: IV ampicillin + gentamicin (or + cefotaxime), cover GBS/Gram-negatives/Listeria. Chlamydia trachomatis neonatal pneumonia → oral macrolide (erythromycin/azithromycin).

Oxygen delivery (commonly asked)

Device	Typical flow	Approx FiO₂
Nasal prongs/cannula	0.5–2 L/min (infants), up to 4 L/min	Up to ~0.4; preferred in infants — low flow, well tolerated
Nasopharyngeal catheter	0.5–1 L/min	Similar; needs humidification, risk of gastric distension
Simple face mask	5–8 L/min (min 5 to flush CO₂)	0.35–0.5
Non-rebreather mask	10–15 L/min	up to ~0.95
CPAP / HFNC	—	For severe hypoxaemia/failure not corrected by standard O₂

High-yield: Nasal prongs are the preferred oxygen delivery method in young infants with severe pneumonia; target SpO₂ ≥ 90%.

Treatment flow: Classify severity → SpO₂ check → if <90% give O₂ → choose antibiotic by age & severity → reassess at 48–72 h → if no improvement, escalate / image / look for complication (empyema, resistant organism, TB, foreign body)

Complications

• Parapneumonic effusion → empyema (commonest complication; S. pneumoniae, S. aureus, Strep pyogenes) — needs intercostal drainage ± intrapleural fibrinolytics or VATS.
• Pneumatocoele, lung abscess, necrotising pneumonia, pneumothorax / pyopneumothorax — classically S. aureus.
• Bacteraemia/sepsis, metastatic infection (meningitis, septic arthritis).
• Bronchiectasis (post-necrotising, recurrent).
• Respiratory failure, SIADH, haemolytic anaemia (cold agglutinins with Mycoplasma).
• HUS with pneumococcal (neuraminidase-mediated) infection.

High-yield: Pneumatocoele + empyema = think Staphylococcus aureus. Cold agglutinin haemolysis = think Mycoplasma.

Key differentials

Condition	Clue to distinguish
Bronchiolitis	< 2 yr, RSV, wheeze + hyperinflation, expiratory distress; no focal consolidation
Acute asthma	Recurrent wheeze, atopy, reversibility, bilateral wheeze, afebrile
Foreign body aspiration	Sudden choking, unilateral hyperinflation/atelectasis, recurrent same-lobe pneumonia
Pulmonary TB	Chronic cough >2 wk, weight loss, contact history, hilar lymphadenopathy
Congestive heart failure	Hepatomegaly, gallop, cardiomegaly, bilateral basal crepts
Bronchopneumonia vs lobar	Patchy bilateral vs single lobe consolidation
Empyema vs effusion	Both dull/absent breath sounds; pleural tap differentiates

Prevention (high-yield public health)

• Vaccines: PCV (pneumococcal conjugate vaccine) and Hib vaccine are the key preventive measures — both in India's Universal Immunisation Programme. Also measles and pertussis vaccination reduce pneumonia burden/secondary infection.
• Exclusive breastfeeding for 6 months, adequate nutrition (prevent malnutrition/Vitamin A deficiency), reduce indoor air pollution, hand hygiene.
• Zinc supplementation reduces pneumonia incidence; routine zinc is part of diarrhoea, and considered adjunct in some settings.

Recently asked / exam angle

• WHO 2014 reclassification — "chest indrawing pneumonia" now treated at home with oral amoxicillin; old "very severe pneumonia" merged into "severe pneumonia." (Very frequently tested as a "what changed" question.)
• Fast-breathing cut-offs by age (60/50/40/30) — direct recall, almost guaranteed.
• Commonest cause of pneumonia in under-5 = viral (RSV); commonest bacterial = S. pneumoniae.
• Afebrile pneumonia + conjunctivitis in a 1–3 month infant = Chlamydia trachomatis → macrolide.
• Pneumatocoele on CXR → S. aureus.
• Drug of choice for non-severe CAP = high-dose oral amoxicillin (80–90 mg/kg/day, 5 days).
• Severe pneumonia inpatient regimen = ampicillin + gentamicin, oxygen if SpO₂ < 90%.
• Mycoplasma features — walking pneumonia, bullous myringitis, cold agglutinins, extrapulmonary (skin, neuro, haemolysis); treat with macrolide.
• SpO₂ < 90% as the oximetry threshold for severe disease / oxygen.
• Difference between IMNCI under-2-month vs 2-month–5-year algorithms.

Rapid revision

1. Fast-breathing cut-offs: <2 mo ≥60, 2–12 mo ≥50, 1–5 yr ≥40, ≥5 yr ≥30 breaths/min.
2. Lower chest indrawing = hallmark sign; under WHO 2014 it is "pneumonia," treat with oral amoxicillin if no danger signs.
3. SpO₂ < 90% or central cyanosis = severe pneumonia → oxygen + injectable antibiotic + referral.
4. Commonest overall cause under-5 = RSV (viral); commonest bacterial = Strep pneumoniae.
5. Neonate afebrile pneumonia + conjunctivitis + eosinophilia = Chlamydia trachomatis → erythromycin/azithromycin.
6. School-age walking pneumonia, cold agglutinins, bullous myringitis = Mycoplasma → macrolide.
7. Pneumatocoele, empyema, pneumothorax = Staph aureus; add cloxacillin/vancomycin.
8. Drug of choice non-severe CAP = high-dose oral amoxicillin 80–90 mg/kg/day × 5 days.
9. Severe pneumonia 1st-line = IV ampicillin + gentamicin; ceftriaxone if no response/resistance.
10. Investigation to confirm = chest X-ray (PA); not routine for uncomplicated outpatient cases.
11. Nasal prongs = preferred O₂ delivery in infants; target SpO₂ ≥ 90%.
12. Prevention = PCV + Hib vaccine, breastfeeding, nutrition, reduce indoor air pollution.