Pneumonia is the inflammation and consolidation of the lung tissue as a result of infection, inhalation of foreign particles or irradiation. Streptococcal is the most common form of pneumonia. The bacteria lives in the body of healthy people but only causes problems when the resistance of the patient has been lowered by another illness or infection. Symptoms include headaches, feverishness, muscle pain and sore throat. Later, coughing becomes the main symptom. Another bacterium, klebsiella pneumoniae, produces a more lethal pneumonia, and occurs almost exclusively in hospitalized patients.