What causes pneumonia primarily?

Pneumonia is primarily caused by a bacterial infection of the lungs. The most common bacteria responsible for pneumonia include Streptococcus pneumoniae, which can invade the lung tissue and lead to inflammation and the accumulation of fluid, impairing the lungs' ability to function properly. This infection can spread to the air sacs (alveoli) of the lungs, causing them to become filled with pus or fluid, which results in the hallmark symptoms of pneumonia, such as cough, fever, and difficulty breathing.

While viral infections and other factors can contribute to respiratory issues, bacterial infections remain the primary pathogenic cause of pneumonia. For instance, viruses may lead to inflammation of the upper respiratory tract, but they are not the predominant cause of pneumonia itself. Allergic reactions and environmental pollutants can exacerbate lung conditions but are not direct causes of pneumonia. Thus, understanding that bacterial infections are the main culprits highlights the importance of both prevention (like vaccinations) and treatment (such as antibiotics) in managing this serious lung condition.