Reduced progression of early carotid atherosclerosis after antibiotic treatment and Chlamydia pneumoniae seropositivity.

BACKGROUND Chlamydia pneumoniae (Cp) infection has been associated with atherosclerosis, and a beneficial effect of antibiotic therapy on future cardiovascular events was described. METHODS AND RESULTS We evaluated the effect of roxithromycin therapy (150 mg twice daily for 30 days) on the progression of the intima-to-media thickness (IMT) of the common carotid artery using duplex ultrasonography in a prospective and randomized trial with a follow-up of 2 years in 272 consecutive patients with ischemic stroke aged over 55 years in whom the first IMT measurement and Cp testing (IgG and IgA) were performed at least 3 years before the roxithromycin treatment. Cp IgG antibodies (> or =1:64) were initially found in 123 (45%) patients and IgA antibodies (> or =1:16) in 112 (41%) patients. During the 3 years before antibiotic therapy, Cp-positive patients showed an enhanced IMT progression, even after adjustment for other cardiovascular risk factors (0.12 [95% CI, 0.11 to 0.14] versus 0.07 [0.05 to 0.09] mm/year; P<0.005). The 62 Cp-positive patients given roxithromycin showed a significantly decreased IMT progression after 2 years compared with the Cp-positive patients without therapy (0.07 [0.045 to 0.095] versus 0.11 [0.088 to 0.132] mm/year; P<0.01). No significant difference in the occurrence of future cardiovascular events was found between both groups during follow-up. No change of IMT was observed in Cp-negative patients given roxithromycin (n=74) compared with those without therapy (0.06 [0.03 to 0.09] versus 0.07 [0.05 to 0.09] mm/year). CONCLUSIONS Our findings suggest a positive impact of antibiotic therapy on early atherosclerosis progression in Cp-seropositive patients with cerebrovascular disease.