Chlamydia Pneumonia and Proliferative Diabetic Retinopathy: Serologic Evidences in a Pilot Study

Purpose: Chlamydia pneumonia is a known endothelial pathogen in several vascular diseases including atherosclerosis, age-related macular degeneration and non-arteritic anterior ischemic optic neuropathy. Diabetic retinopathy is a retinal vascular disease that may similarly be affected. We serologically investigated the presence of C. pneumonia infection in patients with proliferative diabetic retinopathy. Design: Pilot case-control study. Patients & Methods: During a period of 12 months, we examined sera of 27 type I diabetic patients with different stages of diabetic retinopathy for anti-chlamydial IgG and IgA by enzyme-linked immunosorbent assay (ELISA). Results: The IgG seropositivity was significantly different between different diabetic retinopathy groups (P=0.017). Rate of seropositivity was higher among patients with PDR comparing to patients without PDR, with a marginal significance (P=0.062). Although the titer of IgA was negative in all patients (less than 0.357 U/mL), the IgA titer was higher in patients with PDR than those without PDR, reaching the significance at P<0.06 level. Conclusion: C. pneumonia may be an independent risk factor for proliferative diabetic retinopathy.