Pneumonia is a serious infection of one or both lungs, typically caused by bacteria, viruses, fungi, or parasites. Streptococcus pneumonia is a common cause of bacterial pneumonia, and the flu and respiratory syncytial virus (RSV) have been linked to viral pneumonia. These microorganisms grow rapidly in lung tissue, filling infected parts of the lung with fluid and pus.
Symptoms include cough, sometimes with sputum or phlegm; fever; chest pain when inhaling; and shortness of breath. Abnormal chest sounds heard with a stethoscope and a chest x-ray may confirm the presence of pneumonia, but blood tests, urinalysis, or sputum cultures may be required to determine the specific cause of pneumonia and identify the most effective course of treatment. Antibiotics may treat bacterial and fungal pneumonia, but are not effective in combating viral pneumonia.
Nearly 1 million people in the United States are hospitalized with pneumonia each year, according to the Centers for Disease Control and Prevention (CDC). People with viral infections, lung disease, heart disease, swallowing problems, and those who have suffered a stroke or seizure have an increased risk for contracting pneumonia. Several vaccines can lower the risk of developing pneumonia, including the pneumococcal conjugate vaccine, and vaccines to prevent underlying causes, such as influenza, pertussis, and varicella.
Learn more about preventing, treating and managing pneumonia from the CDC .