Pneumonia is a very common condition that affects over three million people in the United States each year. It is an infection that can cause a severe illness in which one or both lungs can fill with fluid or phlegm, mucus that is generated in the lungs. Accumulation of fluid in the lungs can lead to the development of pneumonia. Additionally, an overabundance of mucus in the lungs can cause scarring, and in extreme cases, it can result in significantly more damage to the lungs. Read on to explore the different causes of pneumonia.

1. Bacteria

Bacteria is the leading cause of pneumonia, with Streptococcus pneumonia being the most common etiologic cause of bacterial pneumonia. Bacterial pneumonia caused by Streptococcus can be the result of an infection of this bacterial species or as a secondary infection that can occur following infection with a different bacterial species. Atypical pneumonia is another form of pneumonia that is usually only prevalent during the latter half of the year, primarily during the summer and winter months.  Mycoplasma pneumonia also often leads to the condition. There are also several other types of bacteria that can lead to forms of pneumonia, but most have the same basic side effects and symptoms as those mentioned above.