Demonstration of Chlamydia pneumoniae in tissue by immunohistochemistry

Chronic Chlamydia pneumoniae infection may be difficult to diagnose using routine methods such as culture, antigen detection, serology and polymerase chain reaction (PCR). We describe a method for the immunohistochemical staining of tissue biopsies using a C. pneumoniae-specific monoclonal antibody and a streptavidin/biotin technique. This method provides specific identification of the organism and reveals its actual location in tissues which may or may not be inflamed. Host cells containing C. pneumoniae antigen were easily identified by their bright red color in tissue sections counterstained with hematoxylin.