Pneumonia is a commonly observed infection that can have serious and life threatening consequences in the absence of proper treatment. This infection tends to affect one or both the lungs and is caused by several different types of viruses or bacteria. In some cases, parasites and fungi can also result in pneumonia. Smokers are at a greater risk of suffering from pneumonia. There are three different types of pneumonia and they can be classified based on the organism that causes the infection or the method in which the infection is acquired. Ordinarily the kinds of pneumonia include community acquired pneumonia, healthcare associated pneumonia, hospital acquired pneumonia, atypical pneumonia and aspiration pneumonia.

Among the different types of pneumonia, community acquired pneumonia is the infection that is caused by germs encountered during the normal routine or normal course of activities. This type of pneumonia is rather mild and is caused by common germs. Community acquired pneumonia is caused by several different types of bacteria, viruses, fungi and some parasites as well. Bacteria like streptococcus pneumonia, haemophilus influenza, klebsiella pneumonia and staphylococcus aureus may cause this infection. Methicillin resistant staphylococcus aureus may also cause this condition as can mycoplasma pneumonia, which is an organism similar to bacteria. Some viruses that are responsible for causing flu may also cause pneumonia.

Health care acquired pneumonia is an infection that tends to be a problem in several health care centers like hospitals, outpatient centers, nursing homes, kidney dialysis centers etc. This is common and among the most prevalent types of pneumonia and is caused by some strains of haemophilus influenza and streptococcus pneumonia. In many cases of health care acquired pneumonia, the bacteria tend to develop resistance to some of the standard antibiotics. Patients in intensive care sections and those on ventilators tend to be particularly susceptible to this condition.

Aspiration pneumonia is also one of the important types of pneumonia and this tends to occur when a person breathes a foreign substance in the lungs. This type of pneumonia may occur if a person vomits after being unconscious or while sleeping and then accidentally breathes in the contents. In some diseases like Parkinson's disease or amyotrophic lateral sclerosis, the person may face difficulty in swallowing and this may cause aspiration pneumonia.

In some cases people having weak immune systems also tends to suffer from pneumonia. In these cases, opportunistic pneumonia bacteria tend to affect those suffering from weak immune system caused by organ transplant or due to use of medication taken to suppress the immune system. Atypical pneumonia is also one of the types of pneumonia and this can be passed from one individual to another. Certain bacteria like mycoplasma pneumonia, chlamydophila pneumonia and legionella pneumophila are responsible for causing this condition. It is extremely important to identify the type of pneumonia so that the correct treatment for the condition can be started at an earliest. The wrong line of treatment or delay in starting the treatment can result in several complications and in some cases it can also result in a fatality.