title: Autoimmunohistochemistry: a new method for the histologic diagnosis of infective endocarditis.
abstract: BACKGROUND
  Although the pathologic examination of cardiac valves remains the reference standard for the diagnosis of infective endocarditis, the detection of microorganisms often poses a challenge for pathologists. This can be done by use of nonspecific histochemical stains or by immunohistochemical analysis, but specific antibodies are often not available. We describe a novel method for the detection of microorganisms in valve specimens from patients with infective endocarditis.
  
  
  METHODS
  Detection of microorganisms was performed in valve specimens from patients with endocarditis caused by gram-positive cocci (25 specimens), blood culture-negative endocarditis (15 specimens: 6 cases caused by Coxiella burnetii, 5 caused by Tropheryma whipplei, and 4 caused by Bartonella species), or noninfective degenerative damage (30 specimens, used as negative controls), using the patients' own serum. This technique, called "autoimmunohistochemistry," is an immunohistochemical peroxidase-based method that we compared with results of culture and polymerase chain reaction (PCR) assay.
  
  
  RESULTS
  Bacteria were detected by autoimmunohistochemistry in 20 (80%) specimens from patients with endocarditis caused by gram-positive cocci and in 15 (100%) specimens from patients with blood culture-negative endocarditis but in no control specimens. The rate of detection of bacteria by autoimmunohistochemistry was significantly higher than that by culture but was similar to that by PCR.
  
  
  CONCLUSIONS
  Autoimmunohistochemistry may be useful for the detection of microorganisms in samples of valves from patients with infective endocarditis. This new diagnostic tool may be particularly useful in cases of blood culture-negative endocarditis.
authors.affiliation: Unite des Rickettsies et des Pathogenes Emergents, Centre National de la Recherche Scientifique, Unite Mixte de Recherche 6020, Institut Federatif de Recherche 48, Universite de la Mediterranee, Marseille, France. hubert.lepidi@medecine.univ-mrs.fr
authors.forename: Hubert
authors.initials: H
authors.lastname: Lepidi
authors.forename: Bema
authors.initials: B
authors.lastname: Coulibaly
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Casalta
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
mesh_terms: D000192:Actinomycetales / Q000276:immunology / Q000302:isolation & purification; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000276:immunology; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D001473:Bartonella / Q000276:immunology / Q000302:isolation & purification; D016997:Coxiella burnetii / Q000276:immunology / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis; D004697:Endocarditis, Bacterial / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006095:Gram-Positive Cocci / Q000302:isolation & purification; D006351:Heart Valves / Q000382:microbiology*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D004269:DNA, Bacterial