ARYA Atherosclerosis2320101208THE INFLUENCE OF CHLAMYDIA PNEUMONIAE INFECTION ON INTIMA-MEDIA-THICKNESS (IMT) IN COMMON CAROTID ARTERY157157ENFreshteAshtariVahidShayegan-nejadAlirezaKhosraviAliaSaberiMD. Resident of Neurology, Department of neurology, Isfahan University of medical science, Isfahan, Iran.. a_saberi@resident.mui.ac.irMonir AzamNiknazar20101208  Abstract INTRODUCTION: Atherosclerosis is a multifactorial disease and the identification and diagnosis of its risk factors can help prevent its complications. Among the recently introduced risk factors is infection with Chlamydia pneumoniae. Atherosclerosis is initially characterized by increased intima-media-thickness (IMT), which can be measured by duplex ultrasonography. This study was designed to assess the role of Chlamydia pneumoniae infection in increasing IMT. methods: Extracranial carotid duplex ultrasound was done in 83 individuals and IMT was measured 1 centimeter proximal to bifurcation of the common carotid arteries. IMT more than 0.9 mm was considered as increased. Forty-four individuals had increased IMT and were included in the case group; 39 individuals with normal IMT were considered as the control group. These two groups were matched for age, sex, smoking, and underlying diseases. Chlamydia pneumoniae IgG (Cp.IgG) and Chlamydia pneumoniae IgA (Cp.IgA) were measured in these 2 groups by using the ELISA method and titers more than 1.10 ISR (Immune Status Ratio) were defined as positive, 0.9-1.09 ISR as borderline, and less than 0.9 ISR as negative. We compared the prevalence of Cp.IgG and Cp.IgA seropositivity and the means of antibody titers in these 2 groups. results: There was no significant difference in the prevalence of Cp.IgG and Cp.IgA seropositivity and in the mean titers of these antibodies between the case and control groups. CONCLUSIONS: Cp.IgG and Cp.IgA do are not valuable predictors of increased IMT.     Keywords: Chlamydia pneumoniae, Intima Media Thickness, Serum Antibody