Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. A variety of organisms, including bacteria, viruses and fungi, can cause pneumonia. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these from infecting your lungs, but sometimes these germs can overpower your immune system, even if your health is generally good.







