Chlamydia pneumoniae is a human respiratory pathogen that causes acute respiratory disease and approximately 10% of community-acquired pneumonia. The infections are geographically widespread. Antibody prevalence studies have shown that virtually everyone is infected with the C. pneumoniae organisms at some time and that reinfection is common. In addition to respiratory disease, seroepidemiologic studies have shown an association of this organism with coronary artery disease. C. pneumoniae was detected in coronary artery atheromas by immunocytochemistry (15/36) and by polymerase chain reaction (PCR) (13/30) in 20 of 36 autopsy cases from Johannesburg, South Africa. Sequence analysis of the C. pneumoniae rRNA genes amplified by PCR confirmed that the amplified gene products were C. pneumoniae. Electron microscopy revealed typical pear-shaped C. pneumoniae elementary bodies in 6 of 21 atheromatous plaques. These findings support the seroepidemiologic studies and offer further evidence that C. pneumoniae may be involved in the atherosclerotic process.
Aims-(1) To seek evidence of the existence of Chlamydia pneumoniae in a spectrum of atheromatous lesions in diVerent types of arteries from individuals of diVerent ages, using a polymerase chain reaction (PCR) assay supported by electron microscopy and immunocytochemistry; (2) to use electron microscopy to examine interactions between C pneumoniae and the cells present in the arterial tissue; (3) to assess the extent to which the data fulfil the criteria for causality. Methods-At necropsy examination, 35 arterial specimens were taken from 25 subjects. The grade of atheroma was determined macroscopically and microscopically and the tissues coded and examined by the three techniques. Results-Of the 35 specimens, 24 had macroscopic or microscopic atheromatous lesions of varying degree. Twenty two of the 35 specimens were examined by electron microscopy, C pneumoniae-like bodies being found in 11 (50%); seven specimens were examined by the immunocytochemical method, positive staining being detected in three; and all specimens were examined by the PCR technique, 15 (43%) being PCR positive. Overall, of the 24 specimens with lesions, 17 (71%) were positive by at least one of the three tests, whereas of the 11 specimens without lesions, only one was positive. The positive specimens comprised 10 of 19 aortas, three of six iliac arteries, and one coronary and one pulmonary artery. C pneumoniae was detected in four of six specimens in which there were early changes and in a 20 year old subject. Concerning the 25 subjects, of 17 who had atheromatous arteries, 14 (82%) were C pneumoniae positive and of the eight who had normal arteries, none was positive. Conclusions-There is a strong correlation between C pneumoniae and arterial atheromatous lesions. The organism may contribute to the disease process by damaging smooth muscle cells. (J Clin Pathol 1998;51:812-817)
The antigen-specific serological response to Chlamydia pneumoniae was studied in 45 adults with coronary artery atherosclerosis and compared with that in 40 adults with acute respiratory infection. C. pneumoniae antigen and DNA were detected in lesions more frequently in patients with low immunoglobulin G titers against C. pneumoniae than in those with high immunoglobulin G titers. Reactivities with the 42-kDa (46%) and 52-kDa (31%) proteins were observed more frequently in sera from seropositive individuals with atherosclerosis than in sera from patients with acute respiratory infection. Antibodies against the C. pneumoniae-specific 42and/or 52-kDa protein may be a marker for chronic C. pneumoniae infection.
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