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Pneumonia is a common infection of the lungs affecting mostly the microscopic air sacs – the alveoli. The function of the respiratory system is to exchange oxygen and carbon dioxide between the body and the environment. This process takes place in the alveoli of the lungs. Inhaled oxygen moves from the alveoli into the blood in the capillaries while carbon dioxide relocates from the blood to the alveoli to be exhaled out of the body. In people with pneumonia, these air sacs are filled with fluid or pus, hindering the gas exchange process, resulting in difficulty breathing and a cough reflex. Other symptoms may include chest pain, fever, chills and confusion.
Pneumonia is not a single disease. A large number of various organisms can cause pneumonia. Bacterial pneumonia is the most common, with Streptococcus pneumoniae being the main culprit. Viral pneumonia is more common in young children. A variety of viruses are implicated with each of them predominating in different times of the year.
Pneumonia commonly starts as an infection of the upper respiratory tract – a cold or flu, which then spreads to the lungs. The most common routes of transmission are through inhalation of contaminated aerosol droplets and aspiration of oral bacteria into the lungs.
The setting in which pneumonia develops is an important information as it helps to identify the source of the causative agent and hence the treatment approach. Generally, community-acquired pneumonia is less dangerous than health care-associated, hospital-acquired, or ventilator-associated pneumonia. This is because an infection contracted outside health care facilities is less likely to involve multidrug-resistant bacteria. Patients who are already in hospitals are also most likely to have other health problems and weakened immune system and are thus less able to fight the disease.
Pneumonia is often diagnosed based on physical exams and a chest X-ray. Clinical assessment for children is primarily based on a rapid respiratory rate, a cough, presence of lower chest wall indrawing, and the level of consciousness. Adults are usually checked for vital signs and presence of chest crackles – the rattling noise coming from a diseased lung.
Bacterial pneumonia is treated with antibiotics. The choice of antibiotics depends on the patient’s age, health conditions and how the infection was acquired. Viral pneumonia caused by influenza viruses may be treated with antiviral drugs. Hospitalization may be required for severe cases with breathing difficulty, especially for young children, the elderly, and those with other health problems.
