Diagnostic performance of immunohistochemistry for the aspergillosis and mucormycosis

Abstract

Summary Objective To investigate the accuracy of immunohistochemistry (IHC) tests for distinguishing between mucormycosis and aspergillosis and compare the clinical characteristics of mucormycosis patients according to galactomannan (GM) results. Methods We evaluated diagnostic performance of IHC test with tissue sections of patients with culture‐proven invasive fungal infection. In addition, we conducted PCR assay with tissue sections of mucormycosis patients with positive GM results to evaluate the possibility of co‐infection. Results In culture‐proven mucormycosis (n = 13) and aspergillosis (n = 20), the sensitivity and specificity of IHC test were both 100% for mucormycosis and 85% and 100%, respectively, for aspergillosis. Among the 53 patients who met the modified criteria for proven mucormycosis and had GM assay results, 24 (45%) were positive. Compared with those with negative GM results (n = 29), mucormycosis patients with positive GM results had significantly higher incidence of gastrointestinal tract infections (6/24 [25%] vs 0/29 [0%], P = .006) and were more likely to be histomorphologically diagnosed as aspergillosis (7/24 [29%] vs 2/29 [7%], P = .06). PCR assay amplified both Aspergillus‐ and Mucorales‐specific DNA in 6 of these 24 cases. Conclusions Immunohistochemistry tests seem useful for compensating for the limitations of histomorphologic diagnosis in distinguishing between mucormycosis and aspergillosis. Some proven mucormycosis patients with positive GM results had histopathology consistent with aspergillosis and gastrointestinal mucormycosis. In addition, about one quarter of these patients revealed the evidence of co‐infection with aspergillosis by PCR assay.

Risk factors for mortality in patients with pulmonary mucormycosis

“…22,23 We also found previously that 45% (24/53) of proven mucormycosis cases gave positive galactomannan results, and in 25% (6/24) of those cases there was polymerase chain reaction evidence of co-infection with aspergillosis and mucormycosis. 4 In the present study, more than a third (36% Solid organ transplant 3 (11) 3 (17) .67…”

“…The IHC protocol has been described [3,12]. 4,12 Clinical data including demographics, pre-existing medical conditions, laboratory findings, microbiological data, antifungal therapy and outcomes were collected, and risk factors for 90-day mortality of PM were analysed. This observational study was approved by the institutional review board of Asan Medical Center (IRB No.…”

“…4 Probable PM was defined as (a) presence of host factors together with clinical factors, such as dense, well-circumscribed lesions with or without halos or reverse halo signs, and air-crescent signs or cavities on CT, and mycological evidence for mucormycosis agents in non-sterile culture (sputum or bronchoalveolar lavage fluid) or (b) histological evidence of tissue invasion by hyphae, with positive mucormycosis immunohistochemical staining from sites other than lung and radiological evidence of pulmonary involvement. 4 Prolonged neutropenia was defined as absolute neutrophil count <500 cells/μL for more than 10 days. Corticosteroid therapy was defined as (a) the standard dose when more than 0.3 mg -1 •kg -1 •day -1 systemic prednisolone equivalent was administered over three weeks, and (b) any dose when more than 5 mg systemic prednisolone equivalent was administered over 2 days.…”

“…The disease manifests in pulmonary, rhinocerebral, cutaneous, gastrointestinal or disseminated form. Pulmonary mucormycosis (PM) is most commonly encountered in patients with prolonged neutropenia, and recipients of solid organ or haematopoietic stem cell transplants 2‐4 . Since the overall mortality rate of PM ranges from 50% to 70%, 5 identifying poor prognostic factors is important for improving outcomes.…”

Diagnosis of severe respiratory infections in immunocompromised patients

“…Mucormycosis is diagnosed by sample microscopy, culture, and/or histopathology. Immunohistochemistry is 100% sensitive and 100% specific [90]. Mucorales fungi contain neither BDG nor GM, and negative results from these tests in a patient whose HRCT findings are consistent with IFI, therefore, suggest mucormycosis [91].…”