Pneumonia

Pneumonia is an infection involving the lungs. It may be caused by bacteria, viruses, or parasites. There are more than one hundred microbial causes of pneumonia. However, most cases of pneumonia are due to the following bacteria: Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Morayella (Branhamella) catarrhalis. Clinically, pneumonia is characterized by a variety of symptoms and signs. Cough, which may be productive of purulent (yellow or green), mucopurulent (white with flecks of yellow or green), or "rusty" sputum (reddish-brown due to blood mixed in sputum), is common. Fever, chills, and pleuritic chest pain are other manifestations. Extrapulmonary symptoms such as nausea, vomiting, or diarrhea may occur. There is a spectrum of physical findings—the most common of which is crackles (sounds heard on listening with a stethoscope). Other findings that may be present include dullness to percussion, increased tactile and vocal fremitus, bronchial breathing, and a pleural friction rub. It is important to remember that pneumonia in the elderly may present with a paucity of respiratory symptoms and signs and instead may manifest as delirium. Delirium or acute confusion was found in nearly half of elderly patients with pneumonia studied by Riqueleme and colleagues compared with less than one-third of age- and sex-matched control subjects. Older patients with pneumonia complain of fewer symptoms than do younger patients with pneumonia.

Pneumonia is a common and often serious illness. It is the sixth leading cause of death in the United States. About 600,000 persons are hospitalized with pneumonia each year and there are sixty-four million days of restricted activity due to this illness. One study shows that hospitalization for pneumonia is thirty times more likely among nursing home residents compared to adults living in the community.

Immunization with influenza vaccine once yearly and with pneumococcal vaccine every six years are important measures that can help prevent pneumonia. It is also important for those who smoke tobacco to stop smoking.