Electron microscopy studies elucidate morphological forms of Chlamydia pneumoniae in blood samples from patients diagnosed with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) (LB81)

Abstract

Our previous studies of brain tissues obtained at autopsy have established an association of Chlamydia pneumoniae (Cpn) infection with late‐onset Alzheimer’s disease (AD). Given these findings, we have designed a study using electron microscopy (EM) to determine if various forms of Cpn from geriatric patient’s blood samples could be identified and correlated with cognitive decline associated with AD. Patients, >65 years old, and who participated in this IRB approved study, met well‐defined exclusion criteria prior to being evaluated for cognitive status using the SLUMS and FAST testing assessments. After psychometric testing, blood was drawn from the patients and these samples were prepared for EM and assessed for the presence of Cpn. Our ultrastructural analysis revealed evidence for the presence of Cpn in peripheral blood cells from 12 patients correlated with MCI and AD. Intravacuolar reticulate bodies, elementary bodies, and intermediate bodies characteristic of Cpn were observed in leukocytes from the buffy coat. More specifically, we observed the classical “pear‐shaped” elementary bodies characteristic of Cpn. Immuno‐ EM was performed for positive identification of these various forms of Cpn. Our data indicate that screening for Cpn from blood samples may prove to be a viable biomarker in differentiating cognitive change consistent with stages associated with MCI and AD. Investigating the distinct morphologies of Cpn in human blood samples from the geriatric population by EM, with other frontline diagnostic procedures, may clarify the diagnosis of MCI and late onset AD. Grant Funding Source: Center for Chronic Disorders of Aging