Chlamydia pneumoniae is a type of bacteria that can cause respiratory infections, including pneumonia, bronchitis, and sinusitis. It is primarily spread through respiratory droplets when an infected person coughs or sneezes. Symptoms may include cough, fever, and difficulty breathing, but some people may not show any symptoms at all. This bacterium is different from other types of Chlamydia, which are often associated with sexually transmitted infections. Diagnosis typically involves laboratory tests, and treatment usually includes antibiotics. Most people recover fully with appropriate medical care, but it is important to seek treatment if symptoms arise.