Usefulness of (1-->3)-beta-D-glucan measurement for diagnosis of deep mycosis

The number of deep mycosis has been increasing because of increases in immunocompromised hosts and in fungal colonization associated with increasing use of broad-spectrum antibacterial antibiotics. Based on these phenomenon, a simple test method for an early diagnosis of deep mycosis is urgently desired. We therefore investigated the usefulness of assaying a fungal cell component, (1-->3)-beta-D-glucan (beta-glucan). The amount of beta-glucan was obtained from the difference between the amounts determined using Toxicolor and Endospecy, and the serum levels of more than 10 pg/ml were considered positive signs for beta-glucan. The following results were obtained: We found that beta-glucan was positive in 75% of the patients who had been definitely diagnosed to have mycosis, and in 58.3% of the patients strongly suspected of mycosis. The numbers of beta-glucan positive patients' in these 2 groups of patients were significantly different from that in those without mycosis (14.7%, P < 0.05). Thus a usefulness of beta-glucan measurement for the diagnosis of mycosis was demonstrated. However, beta-glucan was sometimes negative even in patients with fungemia at an early phase of the disease and turned positive several days later. Even in a patient with definite lung mycosis, who had a latent circumscribed lesion (afebrile and CRP-negative), beta-glucan was also negative. From these findings, one should be aware that the beta-glucan test produces false negatives even in patients with definite mycosis and that the test should be repeated during the course of the disease.