title: Application of immunohistochemistry to infections.
abstract: BACKGROUND
  Pathologists play an important role in the diagnosis or exclusion of infectious diseases. Traditionally, the diagnosis of infectious diseases rely on serologic assays and cultures. Serologic results may be difficult to interpret in the setting of immunosuppression, fresh tissue is not always available for culture, and culture of fastidious pathogens can be difficult and may take weeks or months to yield a result. Although some microorganisms or their cytopathic effects may be readily identifiable on routine and/or histochemical stains, often these changes are not specific or are sparse in the sample evaluated. In these cases, additional immunohistochemical stains are often needed to establish the diagnosis of infection.
  
  
  OBJECTIVE
  To review the current value and limitations of the use of immunohistochemistry in the diagnosis of infectious diseases in formalin-fixed tissue samples.
  
  
  METHODS
  Literature in Medline and the authors' own experience.
  
  
  CONCLUSIONS
  Immunohistochemistry has proven to be a useful tool in the diagnosis of infectious diseases in tissue samples. Immunohistochemistry is especially useful in the identification of microorganisms that are present in low numbers, stain poorly, are fastidious to grow, are noncultivable, or exhibit an atypical morphology. Finally, it is important to remember that there may be widespread occurrence of common antigens among bacteria and pathogenic fungi and both monoclonal and polyclonal antibodies must be tested for possible cross-reactivity with other organisms.
authors.affiliation: Division of Surgical Pathology, Department of Pathology, The University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555-0588, USA. ejeyzagu@utmb.edu
authors.forename: Eduardo
authors.initials: E
authors.lastname: Eyzaguirre
authors.forename: Abida K
authors.initials: AK
authors.lastname: Haque
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D003141:Communicable Diseases / Q000175:diagnosis*; D006801:Humans; D007150:Immunohistochemistry
chemical_list: D015415:Biomarkers