title: False-positive Aspergillus galactomannan assay in solid organ transplant recipients with histoplasmosis.
abstract: Post-transplantation histoplasmosis may be acquired via inhalation, may result from endogenous reactivation, or may be derived from the allograft. The Histoplasma and Aspergillus enzyme-linked immunoassays are increasingly being relied upon for rapid diagnosis of fungal infections, especially in immunocompromised patients. We describe 4 cases of solid organ transplant recipients who had histoplasmosis and a falsely positive Aspergillus galactomannan (GM) obtained from the serum or bronchoalveolar lavage (BAL) fluid. We also report our experience, testing for Histoplasma antigen (Ag) in specimens positive for Aspergillus GM. From January 2007 through December 2010, of 2432 unique patients who had positive Aspergillus GM tests, 514 (21%) were tested for Histoplasma Ag, and 27 were found to be positive. Most specimens that tested positive for both Aspergillus and Histoplasma were obtained by BAL. False-positive tests for Aspergillus GM can occur in immunosuppressed patients who have histoplasmosis, and may obscure the correct diagnosis.
authors.affiliation: Department of Medicine and William J. von Liebig Transplant Center, Mayo Clinic, Rochester, MN 55905, USA. vergidis.paschalis@mayo.edu
authors.forename: P
authors.initials: P
authors.lastname: Vergidis
authors.forename: R C
authors.initials: RC
authors.lastname: Walker
authors.forename: D R
authors.initials: DR
authors.lastname: Kaul
authors.forename: C A
authors.initials: CA
authors.lastname: Kauffman
authors.forename: A G
authors.initials: AG
authors.lastname: Freifeld
authors.forename: D C
authors.initials: DC
authors.lastname: Slagle
authors.forename: A B
authors.initials: AB
authors.lastname: Kressel
authors.forename: L J
authors.initials: LJ
authors.lastname: Wheat
mesh_terms: D000328:Adult; D000946:Antigens, Fungal / Q000302:isolation & purification; D001230:Aspergillus / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005189:False Positive Reactions; D005260:Female; D005690:Galactose / Q000031:analogs & derivatives; D006658:Histoplasma / Q000276:immunology / Q000302:isolation & purification; D006660:Histoplasmosis / Q000175:diagnosis*; D006801:Humans; D008351:Mannans / Q000302:isolation & purification*; D008875:Middle Aged; D016377:Organ Transplantation / Q000009:adverse effects*
chemical_list: D000946:Antigens, Fungal; D008351:Mannans; C012990:galactomannan; D005690:Galactose