Infection that fills the air spaces turns breathing into work. Pneumonia is an inflammatory infection of the lung parenchyma in which alveoli fill with fluid or pus, causing cough, fever, chest pain, and difficulty breathing.

Bacteria, viruses, and occasionally fungi are responsible. Community-acquired, hospital-acquired, and aspiration pneumonias differ in likely organisms and treatment. Diagnosis rests on clinical findings, chest imaging, and sometimes microbiological tests. Severity scores help decide outpatient versus inpatient care.

Antibiotics for bacterial pneumonia, supportive oxygen, and fluids form the mainstay of treatment. Vaccines against pneumococcus and influenza reduce incidence. Elderly and immunocompromised patients face higher mortality and need particularly careful management.

• Infection causing inflammation and consolidation of lung tissue
• Produces cough, fever, and respiratory distress
• Caused by bacteria, viruses, or other microbes
• Treated with antimicrobials and supportive care