Life Health Sciences – Science Rules it All

Pneumonia is an acute respiratory illness that has recently developed radiological changes like segmental pulmonary shadowing or pulmonary shadowing that affects more than one lobe of lung.

Depending upon the setting pneumonia can be community acquired, hospital acquired or acquired by patients with impaired immune functions. The community acquired pneumonia causes one million hospital admissions per year in UK.

Spread and risk factors

Microorganisms causing community-acquired pneumonia spread by droplet infection (coughing, sneezing, nasal secretions). The patients are previously well, but have risk factors like cigarette smoking, alcohol consumption, corticosteroid therapy, old age, recent influenza infection, lung disease and contact with sick birds or farm animals.

Symptoms

The patient has short, painful dry cough, fever, malaise and chest pain. The chest pain may be referred to shoulder or abdomen. Latter cough becomes productive with rust colored sputum or blood stained sputum. There is high temperature with rigors. Children may present with vomiting and febrile convulsions. There may be headache and confusion.

Microorganism causing community-acquired pneumonia

From most common organisms to least common organisms in order of sequence these include Streptococcus pneumoniae, Chlamydia pneumoniae, Mycoplasma  pneumoniae, Legionella Pneumoniae, Haemophilus influenza, Staphylococcus aureus, Chlamydia psittaci, Coxiella burnetii and Klebsiella pneumoniae.

Investigations

Radiological examination shows homogenous opacity affecting lobe or segment of lung and it appears within eighteen hours of start of symptoms. Complications of pneumonia like pus cavities in the lung, empyema and enlargement of lymph nodes in the middle part of lungs can also be diagnosed with radiograph. Follow up radiological examination, after patient has received treatment, is necessary to assess resolution of pneumonia.

Other investigations are sputum microscopy and culture, blood examination and culture and serological tests.  In case patient does not improve with treatment and sputum sample cannot be obtained, aspiration of secretions from trachea, bronchi and lower lung is needed to detect microorganism and establish diagnosis. Agglutination tests for pneumococcal antigen in blood, sputum, urine and finding C-reactive proteins are useful tests to diagnose pneumococcal pneumonia. Arterial blood gas analysis is performed for all patients admitted in the hospital.

Blood tests include complete examination of blood cells including total white cell count and differential count. The neutrophils increase in pneumococcal pneumonia. White cell count is normal if pneumonia is caused by atypical agent. When number of white cells is less than normal count, it shows viral or severe bacterial pneumonia.

Management

Oxygen, assisted ventilation and intravenous fluids

High concentration of oxygen is administered to all patients to treat hypoxemia except those with hypercapnia. Assisted ventilation is provided at initial stage of treatment. Intravenous fluids are often needed to rehydrate patient.

Antibiotics

Sputum, blood and urine samples are taken and antibiotic treatment is started according to clinical diagnosis. The antibiotic is changed if needed after detection of microorganism in the laboratory.The antibiotic treatment is continued for 10-14 days.

Analgesics

The analgesics like Paracetamol usually cannot relieve chest pain (pleural pain). So it is treated with medicines having strong analgesic effect. These include injections of morphine and pethidine. But these should be used with caution in patients with poor respiratory function due to their depressive action on respiration.

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