Pneumonia is an inflammation of the lungs caused by bacteria, viruses, or chemical irritants.
It is a serious infection or inflammation in which the air sacs fill with pus and other liquid. Boys are affected by pneumonia more often than girls . There is an increased chance of developing pneumonia in a crowded area. Ten to 15 percent of children with a respiratory infection have pneumonia. The streptococcus pneumoniae is the most common bacterium that causes bacterial pneumonia.