Pneumonia is infection of lung parenchymal tissue[?]. This can be caused by any sort of microorganism ranging from bacteria to viruses[?] to fungi. Doctors classify pneumonias into community acquired pneumonia[?] (both from typical and atypical[?] organisms), nosocomial pneumonia[?], immune compromised pneumonia[?], chronic pneumonia[?] and aspiration pneumonia[?].
Before the advent of antibiotics, pneumonia was often fatal, but most community-acquired pneumonias are readily treatable today. Many patients with pneumonia are treated by their own general practitioner and never admitted to hospital. This is often called walking pneumonia because although they can be very ill the patients are still mobile. Some people with walking pneumonia never realise they are ill at all, but merely feel 'run down[?]' and exhausted.
The most common cause of community-acquired pneumonia is Streptococcus pneumoniae[?], also known as Pneumococcus[?].
Pneumonia is a serious illness, especially among the elderly and the immuno-compromised. AIDS patients frequently contract pneumocystis pneumonia, an otherwise rare form of the disease. Persons with cystic fibrosis are also at very high risk of pneumonia because fluid continually accumulates in their lungs.
In 2003, severe acute respiratory syndrome (SARS), a new form of atypical pneumonia[?], is worrying doctors who fear that it may become a pandemic.
