Comparison between Wako‐WB003 and Fungitec G tests for detection of (1→3)‐β‐D‐glucan in systemic mycosis

The limulus factor G reacts with (13)-β-D-glucan, a major structural component of fungal cell walls. The Fungitec G test is a colorimetric assay that measures the concentration of (13)-β-D-glucan and is used as a serodiagnostic test for deep mycosis. Wako-WB003 is another assay for (13)-β-D-glucan that determines the change in turbidity of the gelatin reaction of limulus factor G with (13)-β-D-glucan. In five rabbits inoculated intravenously with 1 × 107 CFU of Candida albicans, the concentration of (13)-β-D-glucan measured by the fungitec G test increased gradually reaching a peak of 660.9 ± 427.9 pg/ml (mean ± SD) 4 days after inoculation, but to 42.225 ± 41.275 ng/ml on day 6 in the Wako-WB003 test. In one rabbit challenged intravenously with 5 × 106 CFU of C. albicans, (13)-β-D-glucan increased to 101.5 pg/ml on day 4 on the fungitec G test, whereas the level remained below the detection limit of the Wako-WB003 test throughout the course of the disease. We also detected high concentrations of (13)-β-D-glucan in 11 patients with candidemia, 4 with suspected candidemia, 1 with invasive pulmonary aspergillosis, and 12 patients with aspergilloma. The concentration of (13)-β-D-glucan measured by the Fungitec G test was > 150, > 1006.8, 312.1, and 55.6 ± 37.4 pg/ml (range, 20.1–138.0 pg/ml), and by the Wako-WB003 test > 153.000, > 17.70, 153.000 and 2.645 ± 7.248 ng/ml (range, < 25.20 ng/ml) in these patients, respectively. In contrast, the concentration of (13)-β-D-glucan in 9 patients with pulmonary cryptococcosis and 6 with superficial candida colonization ranged from < 13.2 and < 15.3 pg/ml in the Fungitec G test and < 0.53 and < 0.12 ng/ml in Wako-WB003 test. There was a weak relationship between the concentration of (13)-β-D-glucan measured by the Fungitec G test and Wako-WB003 test (r = 0.521). Our results indicate that the sensitivity of the Wako-WB003 test is lower than that of the Fungitec G test. J. Clin. Lab. Anal. 11:73–77. © 1997 Wiley-Liss, Inc.