Abstract
Background:
The diagnosis of infectious diseases has historically been accomplished through microbiologic and serologic means. The majority of pathogens do not easily culture and/or are not detected by routine techniques. Immunohistochemistry (IHC), or the union of morphologic examination and detection of antigens, is an effective diagnostic technique for direct visualization of infectious agents in tissue sections.
Objective: The objective of this study was to assess the diagnostic specificity, sensitivity, and accuracy of immunohistochemistry for the diagnosis of numerous infectious agents such as bacteria, viruses, fungi, and parasites in formalin-fixed tissue samples.
Methods: Clinical and histologic infection-suspecting patients’ archival biopsy samples were optimized for IHC using pathogen-specific antibodies. These were then analyzed for diagnostic concordance and accuracy for correlation with culture and molecular assay data.
Results: IHC identified causative pathogens in 85% of positive cultures and yielded ancillary diagnostic information in 20% of negative samples. It was found to be of tremendous worth for the diagnosis of tuberculosis, cytomegalovirus, and fungal infections.
Conclusion: Immunohistochemistry is beneficial to increase accuracy in infectious diseases for those instances where routine cultures are indeterminate. It offers morphologic background to infection localization and is extremely beneficial to recognize pathogens from formalin-fixed tissues.
Keywords: Immunohistochemistry, Infectious disease, Pathogen identification, Tissue diagnosis, Tuberculosis, Fungal infection, Cytomegalovirus, Diagnostic pathology, Antibody staining, Histopathology