Pneumonia is inflammation of the lung tissue which usually occurs as a result of an infection. The infection causes the airways in the lungs to become inflamed and fill with fluid, so the lungs do not work properly and not enough oxygen can get into the bloodstream.

Pneumonia can develop suddenly within 24 hours or may sometimes come on more slowly, over several days. Complications of pneumonia are more common in older adults, however it can affect any age and can be more serious for infants and young children.

Signs and symptoms Patients with pneumonia typically have a cough, often with purulent or blood-tinged sputum, and may have shaking chills, shortness of breath, or pleuritic chest pain. Fever and sputum production may be absent in elderly people with pneumococcal pneumonia.

Before the introduction of routine vaccination, 1 in every 200 children in the UK was admitted into hospital before their 5th birthday as a result of pneumococcal pneumonia.

Age-standardised death rate per 100,000 population in the over 65s (2007)

Pneumonia can be caused by many organisms, including bacteria, viruses and fungi. The commonest cause of pneumonia in the UK is Streptococcus pneumoniae, with around 42% of cases due to the pathogen.

Pneumonia can affect people of any age. However as people get older (especially over 50) the incidence of CAP dramatically increases, as does the risk of dying from the disease. Pneumonia is of greater risk to patients who have other health conditions, such as a lung condition or a weakened immune system. Patients who smoke also put themselves at a greater risk of pneumonia. The immune system of those with HIV/AIDS is weakened and patients suffering from chronic problems with their heart, liver or kidneys have an increased risk of pneumonia. Pneumonia is also a major complication of influenza.

Pneumonia is often defined as either community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP), depending on whether someone becomes infected in the community or in a hospital setting. CAP is common in the UK, affecting up to 500,000 adults each year.  The UK has one of the highest pneumonia mortality rates in Europe. Five-year mortality from CAP in England and Wales stands at 36-39%.

Secondary pneumonia

Pneumococcal pneumonia can occur as a complication of other infections such as influenza. It is thought that viruses reduce the person’s immunity, making them more vulnerable to bacterial infection. Other biological responses to viral infection, such as damage to mucosal surfaces (lining of the airways in the nose, throat and lungs) and reduced clearance of mucus, also allow pneumococcal bacteria to establish more effectively and cause disease.

COPD

Pneumococcal bacteria are responsible for a significant proportion of chronic obstructive pulmonary disease (COPD) exacerbations, which lead to airway damage and progression of the disease. There are currently about 900,000 people in the UK diagnosed with chronic obstructive pulmonary disease, with an estimated 2.8 million people unaware they have this progressive, potentially terminal disease.

Key points

• Pneumonia is inflammation of the lung tissue which usually occurs as a result of an infection
• The commonest cause of pneumonia in the UK is S. pneumoniae, with around 42% of cases due to the pathogen
• Pneumonia can be defined as either community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP)
• Secondary pneumonia can occur as a complication of other infections such as influenza.
•  Pneumococcal bacteria are responsible for a significant proportion of COPD exacerbations