RESUMO
BACKGROUND: Accurate and timely methods for the diagnosis of histoplasmosis in resource-limited countries are lacking. Histoplasma antigen detection by enzyme immunoassay (EIA) is widely used in the United States (US) but not in resource-limited countries, leading to missed or delayed diagnoses and poor outcomes. Lateral flow assays (LFAs) can be used in this setting. METHODS: Frozen urine specimens were submitted to MiraVista diagnostics for antigen testing from 3 medical centers in endemic areas of the US. They were blinded and tested for the MVista Histoplasma LFA. Patients were classified as controls or cases of histoplasmosis. Cases were divided into proven or probable; pulmonary or disseminated; immunocompetent or immunosuppressed; and mild, moderate, or severe. RESULTS: Three hundred fifty-two subjects were enrolled, including 66 cases (44 proven, 22 probable) and 286 controls. Most of the cases were immunocompromised (71%), and 46 had disseminated and 20 had pulmonary histoplasmosis. Four cases were mild, 42 moderate, and 20 severe. LFA and EIA were highly concordant (κ = 0.84). Sensitivity and specificity of the LFA were 78.8% and 99.3%, respectively. LFA sensitivity was higher in proven cases (93.2%), patients with disseminated (91.3%), moderate (78.6%), and severe disease (80%), and those with galactomannan levels >1.8 ng/mL (97.8%). Specificity was 99.3% in proven cases, 99.3% in patients with moderate or severe disease, and 96.8% in those with galactomannan levels >1.8 ng/mL. Cross-reactivity was noted with other endemic mycoses. CONCLUSIONS: The MVista Histoplasma LFA meets the need for accurate rapid diagnosis of histoplasmosis in resource-limited countries, especially in patients with high disease burden, potentially reducing morbidity and mortality.
RESUMO
BACKGROUND: Patients receiving chemotherapy for acute myeloid leukemia (AML) are at high risk for invasive fungal disease (IFD). Diagnosis of IFD is challenging, leading to interest in fungal biomarkers. The objective was to define the utility of surveillance testing with Platelia Aspergillus galactomannan (GM) enzyme immunoassay (EIA) and Fungitell ß-d-glucan (BDG) assay in children with AML receiving antifungal prophylaxis. METHODS: Twice-weekly surveillance blood testing with GM EIA and BDG assay was performed during periods of neutropenia in the context of a randomized trial of children, adolescents, and young adults with AML allocated to fluconazole or caspofungin prophylaxis. Proven or probable IFD was adjudicated using blinded central reviewers. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for Platelia and Fungitell assays alone and in combination for the outcomes of proven and probable invasive aspergillosis (IA) or invasive candidiasis (IC). RESULTS: Among 471 patients enrolled, 425 participants (209 fluconazole and 216 caspofungin) contributed ≥1 blood specimen. In total, 6103 specimens were evaluated, with a median of 15 specimens per patient (range 1-43). The NPV was >99% for GM EIA and BDG assay alone and in combination. However, there were no true positive results, resulting in sensitivity and PPV for each assay of 0%. CONCLUSIONS: The GM EIA and the BDG assay alone or in combination were not successful at detecting IA or IC during periods of neutropenia in children, adolescents, and young adults with AML receiving antifungal prophylaxis. Utilization of these assays for surveillance in this clinical setting should be discouraged.
