Pneumonia (kids)

Epidemiology

• Common in children; highest incidence in <5 years
  • <5 years: ~40 per 1,000
  • 5–14 years: ~15 per 1,000
• Males more commonly affected
• Variable clinical presentation:
  • Classic: fever, cough, tachypnoea ± grunting
  • Atypical: fever without focus, abdominal pain, meningism
• Tachypnoea alone is not diagnostic
• Auscultation findings are unreliable
  • Small airway disease: crackles may be subtle or late.
  • High respiratory rate: transmitted upper-airway sounds mask fine crackles.
  • Observer variability: paediatric studies show poor inter-observer agreement on crepitations vs normal sounds.
  • Early course: consolidation not yet reached pleura.

Aetiology

1. Viral Pneumonia

• Most common cause, especially in infants
• Common pathogens:
  • RSV (~30%)
  • Influenza
  • Parainfluenza
  • Adenovirus (may cause neutrophilia)
• Clinical features: bilateral signs, wheeze common

2. Bacterial Pneumonia

• More likely with:
  • Lobar/segmental changes on CXR
  • Cavitation or pleural effusion (especially Staph. aureus)
• Pathogens:
  • Streptococcus pneumoniae (<5 years most common)
  • Staphylococcus aureus
  • Mycoplasma pneumoniae
    • Up to 30% of community-acquired pneumonia
    • Mean age ~6.3 ± 3.5 years
    • Associated systemic features: Kawasaki-like illness, erythema multiforme, cold urticaria, Guillain-Barré
  • Chlamydia trachomatis (in infants)

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Clinical Diagnosis

• Diagnosis is clinical if signs of LRTI and other causes (e.g. wheeze, foreign body) excluded
• CXR only if:
  • Suspected severe or complicated pneumonia
• If a child has persistent (or repetitive) fever ≥ 38.5 °C, cough, and tachypnoea above age-specific cut-offs—especially with any sign of increased work of breathing or hypoxaemia—treat and monitor as pneumonia, even when the chest sounds deceptively normal.

Feature	Practical threshold*	Rationale
Fever	≥ 38.5 °C, persistent or repetitive	High, persistent fever is strongly associated with bacterial CAP, but applies to viral as well childrens.health.qld.gov.au
Cough	New or worsening	Indicates airway involvement rch.org.au
Tachypnoea at rest	Age–specific cut-offs (see below)	Most sensitive single sign; normal auscultation does not exclude pneumonia rch.org.auwho.int

*If wheeze/asthma, bronchiolitis, foreign body or metabolic acidosis explain tachypnoea better, reassess.

Age-Specific Tachypnoea Cut-offs – If the rate is above the threshold after the fever has settled (or the child is afebrile), the likelihood of pneumonia rises further.

• < 2 months: ≥ 60 breaths / min
• 2–11 months: ≥ 50 / min
• 12–59 months: ≥ 40 / min
• ≥ 5 years: ≥ 30 / min (many Australian ED tools use CEWT scoring rather than a fixed cut-off)

Supportive “Pattern-Recognition” Clues

Increases Suspicion	Decreases Suspicion
Chest wall recession, grunting, nasal flaring	Isolated wheeze in a preschooler (think viral wheeze/bronchiolitis)
Hypoxaemia SpO₂ < 94 % on room air	No fever, normal work of breathing
New abdominal or chest pain, especially in older child	Bilateral widespread wheeze with good saturations
Toxic appearance, lethargy, poor oral intake	Clear alternative focus for fever
Persisting symptoms > 72 h or deterioration	Rapid response to bronchodilator

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Red Flags for Severe Disease

• Respiratory distress
• Apnoea
• SpO₂ < 90 % on room air – Hypoxaemia or cyanosis
• Marked tachycardia
• Altered mental state
• Suspicion of empyema (dullness, asymmetric expansion) or necrotising disease

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Assessment Clues

• Viral more likely if:
  • Preschool age + wheeze
  • Bilateral signs
• Mycoplasma:
  • Indolent onset
  • Variable: crackles, focal or diffuse wheeze
• Bacterial more likely if:
  • Lobar/segmental consolidation
  • Cavitation, effusion (esp. Staph. aureus)

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Investigations

• CXR:
  • Helpful in focal signs
  • Less useful in diffuse wheeze/crackles
  • Round pneumonia → suggestive of Staph. aureus
• Blood cultures: if admission required
• NPA PCR:
  • Detects viruses (young children) or Mycoplasma (older children)
  • Not useful for bacterial culture
• WCC, CRP, ESR:
  • Not reliable for viral vs bacterial differentiation

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Management

Outpatient (most cases)

• First-line: Amoxicillin 30 mg/kg (max 1g) TDS for 3–5 days
• Second-line: Cefuroxime
• Penicillin allergy:
  • Azithromycin 10 mg/kg (max 500 mg) OD for 3 days
  • Alternative: Doxycycline (>8 years)

Admission criteria

• Age <6–12 months
• Toxic appearance or significant respiratory distress
• Hypoxaemia
• Extensive consolidation/effusion/cavitation on CXR
• Poor oral intake or dehydration
• Failure to respond to 48h oral antibiotics
• Comorbidities (e.g. CHD, immunodeficiency, trisomy 21)
• Social/geographic barriers to follow-up

Inpatient antibiotics (severe cases)

• IV flucloxacillin + 3rd-generation cephalosporin
• If suspected Mycoplasma/Chlamydia or failure of beta-lactam:
  • Add erythromycin, roxithromycin, or azithromycin

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Follow-up

• Routine follow-up CXR not needed unless:
  • Severe or complicated pneumonia
  • Follow-up CXR at 4–6 weeks if indicated

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Protracted Bacterial Bronchitis (PBB)

Diagnostic Criteria

• Wet, moist-sounding cough lasting >4 weeks
• Child otherwise well
• May sound “rattly” on chest exam
• No shortness of breath (except during coughing fits)
• Persistent throughout day/night, worse when lying down

Treatment

• First-line: Amoxicillin-clavulanate (Augmentin) for 2 weeks
• If partial improvement: extend up to 4 weeks