What Is Pneumonia?
Pneumonia is an infection of the lung tissue. In adults, it is generally caused by bacterial infections, though viruses, fungi, and protozoa may also be culprits. The latter microorganisms have become very common as causes of pneumonia in immunosuppressed persons, such as those with HIV infection. However, for those with chronic illnesses, especially cardiac or respiratory diseases, or those at increased risk for pneumonia, there is a pneumococcal pneumonia vaccination available as a preventive measure for the most common of these bacterial infections, streptococcus pneumoniae. In children, pneumonia is most commonly caused by viruses.
