Pneumonia in Children (Bacterial and Viral)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Pneumonia is an infection of the lungs that leads to inflammation of the alveoli, which may fill with fluid or pus, causing difficulty breathing. In children, pneumonia can be caused by bacteria, viruses, or other microorganisms. It can range from mild to severe and is a common cause of hospitalisation in young children.

Aetiology

Pneumonia in children can be caused by a range of bacteria, viruses, or less commonly fungi. The causative organism often depends on the child’s age and other risk factors.

Bacterial Causes:

• Streptococcus pneumoniae – the most common cause of bacterial pneumonia in children.
• Haemophilus influenzae type B (Hib) – more common in unimmunised children.
• Staphylococcus aureus – a cause of more severe pneumonia, often with complications like abscess formation.
• Mycoplasma pneumoniae – common in school-aged children and adolescents (causes "walking pneumonia").

Viral Causes:

• Respiratory syncytial virus (RSV) – the most common viral cause in infants and young children.
• Influenza virus – more common in older children.
• Adenovirus and Parainfluenza virus – other frequent viral causes.

Pathophysiology

Pneumonia occurs when the causative organism infects the lower respiratory tract, leading to inflammation in the alveoli. The alveoli fill with fluid or pus, reducing their ability to facilitate gas exchange. This results in reduced oxygenation of the blood and leads to symptoms like cough, difficulty breathing, and hypoxia.

• Bacterial pneumonia: Characterised by rapid onset, high fever, and purulent sputum. Bacterial pathogens lead to direct invasion and damage of lung tissue.
• Viral pneumonia: Usually more gradual in onset with lower-grade fever, but may predispose the child to secondary bacterial infections.

Risk Factors

• Young age (infants and children under 5).
• Prematurity or low birth weight.
• Pre-existing chronic conditions (e.g., asthma, congenital heart disease).
• Immunocompromised status (e.g., HIV, malnutrition).
• Exposure to tobacco smoke or air pollution.
• Lack of vaccinations (e.g., pneumococcal and Hib vaccines).

Signs and Symptoms

Common signs and symptoms of pneumonia in children can vary depending on the age of the child and the cause (bacterial or viral). Typical symptoms include:

• Bacterial pneumonia:
  • Sudden onset of high fever (above 39°C).
  • Fast and laboured breathing (tachypnoea).
  • Productive cough with green or yellow sputum.
  • Chest pain (especially in older children).
  • Lethargy or confusion (particularly in severe cases).
• Viral pneumonia:
  • Gradual onset of low-grade fever.
  • Dry cough, becoming more productive over time.
  • Wheezing or difficulty breathing.
  • Fatigue and irritability.
  • Sometimes followed by a secondary bacterial infection.
• Other general symptoms can include:
  • Poor feeding (especially in infants).
  • Cyanosis (bluish tint of the skin, lips, or nails).
  • Crackles or abnormal lung sounds on auscultation.

Investigations

Diagnosis of pneumonia in children is primarily clinical, but investigations are often done to confirm the diagnosis and assess the severity:

• Chest X-ray: To confirm the diagnosis and evaluate the extent of the infection (e.g., lobar consolidation for bacterial pneumonia).
• Full Blood Count (FBC): Elevated white blood cell count may indicate bacterial infection.
• Blood cultures: Useful in severe cases to identify the causative organism and guide antibiotic therapy.
• Pulse oximetry: To assess oxygen saturation and detect hypoxia.
• Nasal swab for viral PCR: In cases where a viral cause is suspected (e.g., RSV or influenza).

Management

Management of pneumonia in children depends on the causative organism (bacterial or viral), the severity of the illness, and the child’s age and overall health.

Bacterial Pneumonia:

• First-line antibiotics:
  • For mild to moderate cases: **Amoxicillin** or **co-amoxiclav**.
  • In more severe cases: Hospitalisation with intravenous **ceftriaxone** or **cefotaxime** may be needed.
• Supportive care: Ensure adequate hydration and provide paracetamol or ibuprofen for fever and pain relief.
• Oxygen therapy: Administer if the child is hypoxic (SpO2 < 92%).

Viral Pneumonia:

• Supportive care: Viral pneumonia usually resolves on its own, so management focuses on hydration, fever control (paracetamol or ibuprofen), and rest.
• Antiviral therapy: For cases caused by influenza, **oseltamivir** (Tamiflu®) may be used if the child is immunocompromised, especially if initiated within 48 hours of symptom onset.
• Antibiotics are not needed unless a secondary bacterial infection is suspected.

References

1. NICE (2024). Pneumonia in Children: Diagnosis and Management. Available at: NICE Guidance
2. NHS (2023). Pneumonia in Children. Available at: https://www.nhs.uk/conditions/pneumonia/
3. British Thoracic Society (2023). Guidelines for the Management of Community Acquired Pneumonia in Children. Available at: BTS Guidelines