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 ( greater than or equal to1:64) were initially found in 123 (45%) patients and IgA antibodies (greater than or equal to1: 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.