Diagnostic Techniques

IDPB uses a variety of diagnostic techniques in the evaluation of tissue specimens, including morphologic, antigenic and nucleic acid methodologies. These tests are employed as needed based upon review of the case data and histopathology.

Immunohistochemistry (IHC)

IHC offers several distinct advantages when compared to traditional identification methods. This technique is rapidly expanding the diagnostic capability of the pathologist.

IHC permits rapid agent identification. The technique employs specific antibodies, which localize to the antigens of the etiologic agent of interest. Since this technique uses formalin-fixed tissues, specimen transport is simplified, allowing retrospective studies and minimizing laboratory worker exposure to infectious agents.

IHC is a sensitive and specific test methodology for many microorganisms, and unlike some traditional staining methods, they result in direct, highly interpretable visual evidence of the presence of an infectious agent within tissues. In addition, IHC detects organisms that are difficult to culture and those that cannot be cultured.

IHC provides invaluable information for clinical diagnosis as well as for the study of pathogenesis. IDPB has developed many specific IHC assays for emerging or re-emerging infectious diseases. Currently, IDPB has diagnostic IHC assays for more than 100 etiologic agents, including viral, bacterial, parasitic and fungal organisms. For a number of agents, IHC tests may provide the only reliable methods of detection.

Special Stains

Special stains are useful for detecting bacteria, fungi and parasites in tissues and culture materials. However, they may not confer a specific diagnosis of the organism, and each stain differs in its level of sensitivity.


IDPB currently possesses a battery of PCR-based tests for the detection of many bacteria, viruses, fungi and parasites. IDPB molecular tests have been optimized for formalin-fixed paraffin-embedded tissues.


For some cases of unexplained illness, IDPB possesses limited capability for viral culture of etiologic agents. This technique is dependent on freshly frozen tissues or body fluids and permits additional studies such as immunofluorescence methods or electron microscopy.

Electron Microscopy

Electron microscopy (EM) studies are conducted on cell cultures, tissues and body fluids. Both thin section and negative stain EM are available to assist in the diagnosis and characterization of pathogens. EM examination is conducted on glutaraldehyde fixed tissues or bodily fluids, formalin-fixed paraffin-embedded tissue blocks, prepared EM sections, images and grids.