The overall mortality from community-acquired pneumonia is 5-10 per cent, so it is important to identify and treat patients with this disease promptly.
Annual incidence in the UK is six per 1,000 in the 18-39 age group. This rises to 34 per 1,000 in people aged 75 years and over. So every GP can expect to see several cases each year.
Clinical presentations include cough with shortness of breath of recent onset, chest pain which can often be pleuritic, confusion, which is a common symptom in older people, and sputum production.
Clinical signs include fever, increased respiratory rate, reduced air entry, dullness to percussion and localised extra breath sounds.
Often diagnosis has to be made on clinical features alone and treatment begun before the results of tests are known.
Oxygen saturation can be measured by pulse oximetry to assess the severity of disease and the need for oxygen therapy.
A pulse oximeter is a very useful tool in general practice.
A chest X-ray should be arranged for those with persistent symptoms or signs and for all patients at increased risk of underlying lung cancer, such as those aged over 50 years and smokers.
Other tests recommended for patients admitted to hospital include FBC, U&E, LFT, sputum culture and blood cultures. Patients with severe disease should also be tested for atypical pathogens.
Admission or home care?
Once a diagnosis of pneumonia is made, GPs need to decide whether the patient can be managed safely at home or needs hospital admission.
Studies have identified more than 40 indicators of poor prognosis and complex scoring systems have been developed.
The simplest assessment algorithm is that of the British Thoracic Society. This uses the CURB-65 score, a six point scale that allocates one point each to confusion, urea >7mmol/l, respiratory rate [s40]30 per min, systolic BP [s39]90mmHg, diastolic BP [s39]60mmHg and age [s40]65 years.
Patients with one point are likely to be suitable for home treatment, those with two points should be considered for hospital-supervised treatment, and patients with a score of three or more should be managed in hospital as severe pneumonia.
Clinical judgment is needed when using the scoring system. If the score is low but the patient is unwell they could still have severe pneumonia. For example, a young person with normal blood pressure but low oxygen saturation could have severe pneumonia and will need admission.
Treatment at home
For patients managed at home, oral amoxicillin 500-1,000mg three times daily is the preferred choice. Macrolides are an alternative, and for patients with penicillin hypersensitivity, oral erythromycin 500mg four times daily or clarithromycin 500mg twice daily, are recommended. Appropriate antibiotic treatment should be continued for seven days.
Other management strategies for home care include advising patients with suspected community-acquired pneumonia to rest, drink plenty of fluids and avoid smoking. Simple analgesia (such as paracetamol) can be used to relieve pleuritic pain.
Nutritional supplements may be considered in prolonged illness.
Review after 48 hours
Patients should be reviewed after 48 hours, or earlier if indicated. Hospital admission or chest X-ray should be considered for patients who are failing to improve. Sputum examination may be necessary if there is no response to first-line antibiotic, although it is an unreliable test.
Persistent productive cough may indicate TB. Consider microscopy and culture for Mycobacterium tuberculosis, particularly if there are other TB symptoms, such as malaise, weight loss or night sweats, in at-risk patients.
Other causes to consider include Legionnaire's disease and mycoplasma.
Pneumococcal pneumonia vaccination is recommended for patients over the age of 65, those with decreased immunity, for example after splenectomy or with sickle cell disease, and those with heart or lung disease.
Influenza vaccine is recommended every year for healthcare workers, older people and people with chronic conditions such as emphysema, diabetes, heart disease and kidney disease.
Infants in the first 13 months receive three doses of vaccine to protect against Haemophilus influenzae type-B, pneumonia and septicaemia.
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Dr Merriman is a GP in Oxford