Laboratory Research About Detection Of Plama Beta-D-glucan For The Diagnosis Of Systemic Fungal Infection

Because of the abuse of antibiotics and immune inhabitants, the incidences of systemic fungal infection have increased greatly, contributing to a high mortality rate. Therefore, it is very important to diagnose the systemic fungal infection as early as possible. Much work has been done to help the diagnosis of systemic fungal infection according to the fungus components and the metablites, and one of the most dramatic methods is (1->3)-beta-D-glucan. In the present day, we established systemic candidiasis model and systemic aspergillosis model and detected the levels of plasma (1->3)-beta-D-glucan by a G test. We also made tissue biopsy and fungus culture to compare them with G test in the early diagnosis of systemic fungal infection. It was reported first in China to do so. There were forty rats with systemic candidiasis which were divided into four groups, with ten rats in each group. The G test results showed positive after 3 hours being infected, and the sensitivity, specificity, positive predictive rate and negative predictive rate were 80%, 100%, 100% and 55.6% respectively. They were significantly higher than those of control group. There were forty rats with systemic aspergillosis which were divided into four groups, with ten rats in each group after being immunoimpressed by cyclophosphamide. The results showed positive after 24 hours being infected, and the sensitivity,specificity, positive predictive rate and negative predictive rate were 70%, 100%, 100% and 45.4% respectively. They were significantly higher than those of control group. The positive results of G test were much earlier than those of tissue biopsy. Intravenous itraconazole were given to treat the forty rats with systemic candidasis and the results showed that the levels of plasma (1->3)-beta-D-glucan decreased significantly following the therapy.The results suggest that detecting plasma beta-D-glucan by G test is sensitive and specific, and can show the positive results in the early stage of infection. It is paralleled with plasma beta-D-glucan. According to the research results, the method of G test has a high value in the early diagnosis of systemic fungal infection and can be used in the surveillance of the effective treatment.