Pneumonia

Pneumonia is simply an infection of the lung tissue. It causes inflammation of the lung tissue and sputum filling the airways and alveoli. Pneumonia can be seen as consolidation on a chest xray. It can be caused by a bacteria, virus or atypical bacteria such as mycoplasma.

 

Presentation

  • Cough (typically wet and productive)
  • High fever (> 38.5ºC)
  • Tachypnoea
  • Tachycardia
  • Increased work of breathing
  • Lethargy
  • Delirium (acute confusion associated with infection)

 

Signs

There may be a derangement in basic observations. These can indicate sepsis secondary to the pneumonia:

  • Tachypnoea (raised respiratory rate)
  • Tachycardia (raised heart rate)
  • Hypoxia (low oxygen)
  • Hypotension (shock)
  • Fever
  • Confusion

 

There are characteristic chest signs of pneumonia:

  • Bronchial breath sounds. These are harsh breath sounds that are equally loud on inspiration and expiration. These are caused by consolidation of the lung tissue around the airway.
  • Focal coarse crackles caused by air passing through sputum similar to using a straw to blow into a drink.
  • Dullness to percussion due to lung tissue collapse and/or consolidation.

 

Causes

Bacterial

  • Streptococcus pneumonia is most common
  • Group A strep (e.g. Streptococcus pyogenes)
  • Group B strep occurs in pre-vaccinated infants, often contracted during birth as it often colonises the vagina.
  • Staphylococcus aureus. This causes typical chest xray findings of pneumatocoeles (round air filled cavities) and consolidations in multiple lobes.
  • Haemophilus influenza particularly affects pre-vaccinated or unvaccinated children.
  • Mycoplasma pneumonia, an atypical bacteria with extra-pulmonary manifestations (e.g. erythema multiforme).

 

Viral

  • Respiratory syncytial virus (RSV) is the most common viral cause
  • Parainfluenza virus
  • Influenza virus

 

Investigations

A chest xray is the investigation of choice for diagnosing pneumonia. It is not routinely required, but can be useful if there is diagnostic doubt or in severe or complicated cases.

Sending sputum cultures and throat swabs for bacterial cultures and viral PCR can establish the causative organism and guide treatment. All patients with sepsis should have blood cultures. Capillary blood gas analysis can be helpful in assessing or monitoring respiratory or metabolic acidosis and the blood lactate level in unwell patients.

 

Management

Pneumonia should be treated with antibiotics according to local guidelines.

Amoxicillin is often used first line. Adding a macrolide (erythromycin, clarithromycin or azithromycin) will cover atypical pneumonia. Macrolides can be used as monotherapy in patients with a penicillin allergy.

IV antibiotics can be used when there is sepsis or a problem with intestinal absorption.

Oxygen is used as required to maintain saturations above 92%.

 

Recurrent Lower Respiratory Tract Infections

When a child is having recurrent admission requiring antibiotics for a lower respiratory tract infections it is worth considering further investigations for underlying lung or immune system pathology.

A thorough history (including family history) and examination is needed to assess for reflux, aspiration, neurological disease, heart disease, asthma, cystic fibrosis, primary ciliary dyskinesia and immune deficiency.

The following tests can be done:

  • Full blood count to check levels of various white blood cells.
  • Chest xray to screen for any structural abnormality in the chest or scarring from the infections.
  • Serum immunoglobulins to test for low levels of certain antibody classes indicating selective antibody deficiency.
  • Test immunoglobulin G to previous vaccines (i.e. pneumococcus and haemophilus). Some patients are unable to convert IgM to IgG, and therefore cannot form long term immunity to that bug. This is called an immunoglobulin class-switch recombination deficiency.
  • Sweat test to check for cystic fibrosis.
  • HIV test, especially if mum’s status is unknown or positive.

 

Last updated August 2019
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