Study On Early Diagnosis Of Invasive Aspergillosis Disease In Patients With Hematological Disease

BackgroudAspergillus is airborne in all environments, both inside and o-utside the hospital. It is the main pathogen of causing invasive aspergillos-is(IA)in immunocompromised patients. IA occurs mainly in immunosuppre-ssed hosts,such as acute leukemia,bone marrow stem cell transplantation,so-lid organ transplantation,chemotherapy in patients with malignant tumors.T-he epidemiology of patients showed that the incidence of IA has increased considerably in recent years. The incidence of which exceeded candidiasisin the autopsy cases. The mortality rates are very high which more than 40%, It remains a high mortality(80%-100%) among these patients. Clinical signs and symptoms of IA are non-specific. The traditional techniques in laboratory lack sensitivity and waste time. They have a limited role in the diagnosis of IA. Therefore, how to improve the specific diagnostic of IA has become a hot problem of common concern to medical workers at ho-me and abroad. At present, serological methods and molecular biology methods are the most promising.Objective: (1)To evaluate the value of galactomannan(GM)detection for early diagnosis of invasive aspergillosis disease(IA) and monitoring therapy by dectecting galactomannan in high risk patients with hematological disease for invasive aspergillosis disease. (2)Establishing a real-time PCR method for dectecting three aspergillosus, and studing the value of clinical application of the method.Methods:Samples were collected from patients in hematology department from September of 2008 to September of 2009, who were dianogised proven/probable/possible invasive fungal infection basis for China's blood disease/malignant tumors in patients with invasive fungal infections(IFI)of the diagnostic criteria and treatment of the principles of standards. Double-antibody sandwich enzyme-linked immunosorbent assay(ELISA method) and Real-Time PCR were performed to screen for circulating galactomannan(GM)and the concentration of Aspergillus DNA copy number which is defined as positive GM test for detection of a single>0.5,Real-Time PCR in two specimens the mean Ct hole is defined as≤30 positive.54 patients were grouped according to the development of China's blood disease/malignant tumors in patients with invasive fungal infections(IFI)of the diagnostic criteria and treatment of the principles of standards combined with retrospective analysis standard. Sensitivity, specificity and predictive values were calculated respectively and compared.Results:54 patients met the standards. According to the retrospective analysis standard, 13 patients were grouped to proven IA,24 possible IA cases,17 excluded IA cases.(1)The sensitivity, Specificity, positive predictive value(PPV)and negative predictive value(NPV)of the ELISA test were 84.6%.82.4%.78.6%.87.5% respectively. Before GM test, there were 14 clinieal IA patients, After GM test, there were 27 clinical IA patients, the GM test improve the number of clinical diagnosis IA. (2)Before GM test, there were 14 clinieal IA patients, among which 5 patients had major CT imaging with positive rate of 35.7%.2 patients had major CT imaging in 11 possible IA patients who had CT with positive rate of 18.2%. The positive rate of GM test were 80% and 71.4%. Galactomannanemia preceded the development of characteristic findings on CT about 5.5 days. GM test were superior to CT imaging at positive and positive times. GM test is effective when applied for direction of preemptive antifungal therapy.(3)All the patients who were cured, the value of GM were decreased from 1.81±1.07 to 0.95±0.48 in the patients had effective treatment (p=0.000), the GM value had no significant change in the patients of poor prognosis (P=0.748) Quantitive results of the serum-based GM antigen can represent the status of IA and were correlated with the prognosis of IA.(4) The real-time PCR assay amplifies specifically a region of the 18S rRNA gene that is highly conserved in aspergillus species and allows detection of down to 1000fg/ul of Aspergillus DNA. When two-positive results were used to define an episode as'PCR positive',the sensitivity, specificity, PPV and NPV of the PCR test were 92.3%,94.1%,92.3%,94.1% respectively.(5)Two diagnostic detection methods joint evaluation. It shows that the two combined,the sensitivity was 100% and specificity was 76.5%, positive predictive value of 76.5%, negative predictive value was 100%, two joint, improved diagnostic sensitivity and specificity only slightly decreased.Conclusion:GM ELISA test using the cut-off value of>0.5 and Real-Time PCR using the cut-off value of two Ct≤30 had good sensitivity and specificity. Two methods joint can improve diagnostic sensitivity. GM ELISA and Real-time PCR improve positive rate and positive days, which supplied help for early diagnosis of invasive aspergillosis disease. Quantitive results of the serum-based GM antigen can represent the status of IA and were correlated with the prognosis of IA.