Chlamydia pneumoniae (TWAR) is a recently recognized and a new species of the organisms that cause pneumonia. They mainly are the cause behind the acute respiratory diseases that occur. This type is different from the earlier two known species which are responsible for their effects in human beings. The other two species affecting the humans are C. trachomatis and C. psittaci, their DNA are nearly 10% same to the other bacteria that are present. This organism is globally distributed and the infection rate of this organism is more in children who are in the age group between 5 to 14 years. In children the infection caused by TWAR is asymptomatic and quite mild, but it may be more severe and dangerous in adults. Bronchitis and pneumonia are the most common manifestations that are caused due to these infections. TWAR is responsible for around 10% of the pneumonial cases and also for 5% of the bronchitis cases these are the stats in the United States. There is a test that is helpful in detecting the infection this test is known as the micro immuno fluorescence serologic assay; this can easily distinguish between the recent and the past infections.
This organism can easily be isolated in the cell culture; however PCR techniques can also be helpful in facilitating and detecting it in the tissues and clinical specimen too.