Chlamydophilia pneumoniae (also known as Chlamydia pneumoniae) is an obligate intracellular bacterium that causes pneumonia.

Transmission of this infection is thought to occur through respiratory droplets, and institutional outbreaks have been reported. Serologic studies have revealed that many adolescents and most adults are seropositive.

Many patients infected with this pathogen are likely asymptomatic or minimally symptomatic. In symptomatic patients who present for evaluation, fever, cough, and dyspnea are seen. Cough is often nonproductive and may persist for weeks despite therapy.

Clinically, it is not possible to distinguish pneumonia due to C. pneumoniae from pneumonia due to other respiratory pathogens. Also, it is possible to be infected by more than one pathogen at the same time (eg, with Streptococcus pneumoniae and C. pneumoniae). In these cases, it is difficult to determine if C. pneumoniae is responsible for the patient's symptoms or if the other pathogen is more important.

Associations between C. pneumoniae infection and asthma, atherosclerosis, and other chronic conditions have been reported, but the data are not conclusive.

Related topic: community-acquired pneumonia