[Comparison of four diagnostic methods using clinical blood by measuring (1-->3)-beta-D-glucan]

Using Amebocyte lysate of horseshoe crab to measure (1-->3)-beta-D-glucan specifically, a component of the cell wall, several kinds of diagnostic methods for deep mycosis are in practical use in Japan. However, the most important problem is that the judgment of positive or negative is method dependent. To elucidate the cause of the problem, each measurement value of the identical sample by four methods, beta-Glucan Test Maruha (MARUHA), beta-Glucan Test Wako (WAKO). FUNGITEC G Test (FUNGITEC-G) and FUNGITEC G Test MK (FUNGITEC-MK) was compared with the clinical data using 119 cases and 289 tests. Each case was divided into three groups; proven fungal infection, probable fungal infection and non-fungal infection. The negative cases for all the methods tested in the groups of proven fungal infection and probable fungal infection were allergic bronchopulmonary aspergillosis and cryptococcosis, and that for all the methods tested except FUNGITEC-MK method in the group was pulmonary aspergilloma. It seems that these cases cannot be detected correctly by only measuring (1-->3)-beta-D-glucan. On the other hand, the ratio of false positive, positive for non-fungal infection group was high in the case of FUNGITEC-MK. About 23% against the total case was positive for FUNGITEC-MK method, but negative for MARUHA, WAKO, and FUNGITEC-G methods. Although the difference of the sensitivity among four methods was not observed, the specificity, the diagnostic efficiency, and the positive predictive value of FUNGITEC-MK method were remarkably lower than those of the other methods due to false positive measurement. In conclusion, MARUHA, WAKO and FUNGITEC-G except FUNGITEC-MK is not method dependent. It is suggested that FUNGITEC-MK detects non-specific reaction resulted in false positive.