Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.[14] Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing.[15] The severity of the condition is variable.[15]
Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms.[a] Identifying the responsible pathogen can be difficult. Diagnosis is often based on symptoms and physical examination. Chest X-rays, blood tests, and culture of the sputum may help confirm the diagnosis. The disease may be classified by where it was acquired, such as community- or hospital-acquired or healthcare-associated pneumonia.[18]
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