Objective: To investigate the clinical manifestations and the chest imaging characteristics of an epidemic outbreak of respiratory infection caused by Chlamydia pneumoniae (CP).
Methods: A prospective study for CP infection in 15 patients from September 2003 was carried out. Sputum and throat swab specimen were obtained and CP DNA was detected by polymerase chain reaction (PCR). Serum samples were obtained and immunoglobulin G and M (IgG and IgM) of antibodies to CP. pneumoniae were studied by microimmunofluorescence test. Chest X-ray and computed tomography were retrospectively analyzed.
Results: All patients presented fever, headache, sore throat, hoarseness, muscular ache, and dry cough. Acute cough was often associated with chest pain. The sputum blood was present in 3 patients (20%). Moist rales were heard in 4 patients. Chest imaging abnormalities were present in 67% (10 patients). The organism was demonstrated in 87% (13 patients) by PCR. The most common imaging abnormalities were unilateral and (or) bilateral multi-focal or solitary alveolar nodular opacities (9 patients). The patchy shadows were found in 2 patients, and pulmonary consolidation associated with the local pulmonary edema in 1 patient. Hilar or mediastinal lymphadenopathy and pleural effusion was not found.
Conclusions: The colony occurrences and similar clinical and chest imaging manifestations are characteristics of an outbreak of respiratory infection caused by CP in medical workers. An outbreak of respiratory infection caused by CP should be differentiated from severe acute respiratory syndrome (SARS).