The second-generation Histoplasma antigen immunoassay is semiquantitative, expressing results as a comparison to a negative control, which requires repeat testing of the prior specimen with the current specimen to accurately determine a change in antigen. Reporting results in this manner often is confusing to the ordering physician and laboratory. Development of a quantitative assay could improve accuracy, reduce interassay variability, and eliminate the need to test the prior sample with the current sample in the same assay. Calibrators with known concentrations of Histoplasma antigen were used to quantitate antigen in specimens from patients with histoplasmosis and from controls. Samples from cases of disseminated histoplasmosis or other mycoses and controls were tested to evaluate the performance characteristics of the quantitative assay. Paired specimens were evaluated to determine if quantitation eliminated the need to test the current and prior specimens in the same assay to assess a change in antigen. The sensitivity in samples from patients with AIDS and disseminated histoplasmosis was 100% in urine and 92.3% in serum. Cross-reactions occurred in 70% of other endemic mycoses, but not in aspergillosis. Specificity was 99% in controls with community-acquired pneumonia, medical conditions in which histoplasmosis was excluded, or healthy subjects. A change in antigen level categorized as an increase, no change, or decrease based on antigen units determined in the same assay agreed closely with the category of change in nanograms/milliliter determined from testing current and prior specimens in different assays. Sensitivity, specificity, and interassay precision are excellent in the new third-generation quantitative Histoplasma antigen immunoassay.Antigen detection is a useful method for the diagnosis of histoplasmosis (8). Until now, antigen results have been expressed semiquantitatively as antigen units (calculated as enzyme immunoassay [EIA] units [EU]) based upon comparison to a negative control. Antigen levels decline with effective therapy (9, 12) and increase with relapse (13), providing a useful method for monitoring treatment. Based upon analysis of the course of antigen clearance during treatment of histoplasmosis in patients with AIDS (4, 6, 7), a Ն4-EU increase in antigen was chosen as evidence suggesting a relapse of histoplasmosis. In that evaluation, the change in antigen units between current and prior specimens tested concurrently rarely exceeded 4 EU in patients who did not relapse clinically (unpublished observation).Due to interassay variability, prior specimens have been tested simultaneously with current specimens to accurately assess changes in antigen levels. Test reports including current and prior results often are confusing, however, and do not always reach the ordering physician. In this report, a method for quantitation of Histoplasma capsulatum antigen is described, and its performance characteristics, including accuracy, specificity, sensitivity in patients with AIDS and dissemi...

We report results of an immunoassay for Blastomyces dermatitidis antigenuria. Sensitivity was 92.9%, and specificity was 79.3%. Cross-reactions occurred in 96.3% of patients with histoplasmosis, 100% of patients with paracoccidioidomycosis, 70% of patients with penicilliosis marneffei, 2.9% of patients with cryptococcosis, and 1.1% of patients with aspergillosis. Reproducibility was 96.3%. These findings support a potential role for antigen testing in blastomycosis.Most patients with blastomycosis exhibit progressive illnesses that require antifungal therapy. In one study, diagnosis was delayed for more than 1 month in nearly half of the cases (3). Blastomycosis was correctly suspected in only 20% of patients, resulting in unnecessary surgeries and treatment delays (7). In two-thirds of patients who died of acute respiratory distress syndrome caused by blastomycosis, the diagnosis was either not suspected or considered only after the patient became moribund (10).At the University of Mississippi Medical Center, the first testing method for diagnosis was cytology in 58% of cases, KOH in 28% of cases, and histology in 12% of cases (8). The overall sensitivities were 93% for cytology, 85.1% for histology, 66.4% for culture, and 48.4% for KOH preparation. Pathologists who are less experienced with morphological

We have evaluated the Platelia Aspergillus enzyme immunoassay for detection of galactomannan in bronchoalveolar lavage (BAL) specimens in solid organ transplant patients with aspergillosis. The precision and reproducibility in serum or BAL to which galactomannan was added were similar. Sensitivity was 81.8% in patients with aspergillosis, and specificity was 95.8% in lung transplant patients who underwent BAL for surveillance for infection or rejection. Among transplant controls, positive results were more common in patients (i) who underwent diagnostic BAL performed for evaluation of symptoms or chest computed tomographic abnormalities, (ii) who had undergone lung transplantation, or (iii) who were colonized with Aspergillus. Galactomannan testing in BAL is useful for diagnosis of aspergillosis in transplant patients. The significance of positive results in patients without confirmed aspergillosis requires further evaluation.Invasive aspergillosis (IA) is common in hematopoietic stem cell and solid organ transplant patients, and the diagnosis often is determined based on bronchoalveolar lavage (BAL) (11). Galactomannan (GM) antigenemia detection is a useful method for the early diagnosis of IA (7,11,12). Several studies in hematologic patients show that detection of Aspergillus GM in BAL can be a sensitive method for the diagnosis of IA. The sensitivity was 89% or higher, and the specificity was 87 to 100% (1, 9, 10). In two studies that compared BAL and serum, sensitivity was lower in serum than in BAL: 47% versus 100% (1) and 44% versus 89%, respectively (9). False-positive results occurred in patients receiving piperacillin-tazobactam, in whom antigenemia also was present (9). False-positive results have also been reported when Plasmalyte was used to perform BAL (4). Positive BAL results may eliminate the need for additional invasive procedures in some patients (10).We reported previously the detection of Aspergillus GM in BAL from solid organ transplant patients with IA (2, 6). We have further analyzed here those studies and provide additional support for use of BAL testing for diagnosis of IA, including a more detailed analysis of specificity, precision, and reproducibility. MATERIALS AND METHODSClinical materials. The BAL specimens from patients with IA (n ϭ 11) and controls (n ϭ 185) have been previously described (2, 6). Four patients had proven and seven had probable IA, according to published criteria (3). BAL specimens from which Aspergillus or other mold was isolated were considered to be colonized if the patient failed to meet these criteria (i.e., if cultures were not associated with a mold resembling Aspergillus by cytology or histopathology of lung tissue, were not obtained from a sterile site, or were not associated with compatible abnormalities on chest computed tomography [CT] if isolated from a nonsterile site) (5).Transplant controls included 119 lung transplant patients who underwent bronchoscopy to monitor for infection or rejection (surveillance BAL) and 66 patients with a variety of tra...