Effect of Clarithromycin Treatment on Chlamydia pneumoniae in Vascular Tissue of Patients with Coronary Artery Disease: a Randomized, Double-Blind, Placebo-Controlled Trial

Several small clinical trials have indicated that antibiotic treatment of Chlamydia pneumoniae infection is associated with a better outcome in patients with coronary artery disease (CAD). It has not been demonstrated whether antibiotic treatment eradicates C. pneumoniae from vascular tissue. The aim of the present study was to assess the effect of clarithromycin on the presence of C. pneumoniae in the vascular tissue of patients with CAD. Patients who had CAD and who were waiting for coronary artery bypass graft surgery were enrolled in a randomized, double-blind, placebo-controlled trial. Patients were treated with clarithromycin at 500 mg or placebo once daily from the day of inclusion in the study until surgery. Several vascular tissue specimens were obtained during surgery. The presence of C. pneumoniae in vascular tissue specimens was examined by immunohistochemical staining (IHC) and two PCR assays. Chlamydia immunoglobulin G (IgG) titers were determined by an enzyme-linked immunosorbent assay at the time of inclusion in the study and 8 weeks after surgery. A total of 76 patients were included, and 180 vascular tissue specimens were obtained (80 specimens from the group treated with clarithromycin and 100 specimens from the group treated with placebo). Thirty-five patients received clarithromycin (mean duration, 27 days; standard deviation [SD], 12.2 days), and 41 patients received placebo (mean duration, 27 days; SD, 13.9 days). IHC detected the C. pneumoniae major outer membrane protein antigen in 73.8% of the specimens from the group treated with clarithromycin and 77.0% of the specimens from the group treated with placebo (P was not significant). Chlamydia lipopolysaccharide antigen was found in only one specimen from the group that received placebo. C. pneumoniae DNA was not detected in any specimen. Baseline Chlamydia-specific IgG titers were equally distributed in both groups and were not significantly different after treatment. There was no indication of an active C. pneumoniae infection in vascular tissue. Chlamydia-specific IgG titers remained unchanged throughout the study in both the antibiotic- and the placebo-treated patients.