Bacterial Pneumonia Quick Overview
Pneumonia is an infection of the lungs. People with pneumonia usually complain of coughing, mucus production, fever, shortness of breath, and/or chest pain.
- The body's immune system usually keeps bacteria from infecting the lungs. In bacterial pneumonia, bacteria reproduce in the lungs, while the body tries to fight off the infection. This response to bacterial invaders is called inflammation.
- When the inflammation occurs in the alveoli (microscopic air sacs in the lungs) they fill with fluid. The lungs become less elastic and cannot take oxygen into the blood or remove carbon dioxide from the blood as efficiently as usual.
- When the alveoli don't work efficiently, the lungs are less able to extract oxygen from the air. This causes the feeling of being short of breath (dyspnea), which is one of the most common symptoms of pneumonia. Inflammation is the body's attempt to destroy infection, and causes many of the other symptoms of bacterial pneumonia, including fever and chest pain. The lungs themselves do not have any pain fibers but are surrounded by a membrane called the pleura. The pleura does contain many nerve fibers, and if it becomes inflamed by an adjacent infection in the lungs, significant pain can result. This is called pleurisy and often can accompany pneumonia. It is not infrequent, however, for inflammation not to involve the surface of the lung and therefore, little if any pain may be present.
- Pneumonia can be very serious, because it directly interferes with the body's ability to exchange carbon dioxide and oxygen.
- Pneumonia is different from acute bronchitis (another disease that can cause fever, cough, chest pain, and shortness of breath) because acute bronchitis is caused by inflammation in the air passages (called bronchi) leading to the alveoli, not the alveoli themselves. Sometimes it is very difficult, even for a doctor, to tell pneumonia and bronchitis apart. The symptoms and physical examination can be identical. Sometimes a chest X-ray is the only way to distinguish pneumonia from bronchitis. There is also an entity in which both the airways and air sacs are involved with infection, and this is referred to as bronchopneumonia. As noted above, if the surface of the lung is inflamed, pleurisy may result. "Itis" is added to the end of the anatomical location to describe where the inflammation is. The symptoms often follow the location (for example, tracheitis [trachea, the main airway in the lung], laryngitis [larynx or voice box], pharyngitis [throat], bronchitis [bronchi, smaller lung airways], or pneumonitis [pneumonia]).
Medically Reviewed by a Doctor on 11/20/2017
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