👉 Pneumonia is a respiratory illness caused by bacteria, viruses, or fungi that invade the lungs. It can be caused by an infection with a bacterium (such as Streptococcus pneumoniae), a virus like COVID-19, or a fungus like Mycobacterium tuberculosis. Symptoms include coughing up mucus, fever, chest pain, and difficulty breathing. Treatment may involve antibiotics, often given intravenously, to kill the bacteria in the lungs.
