The value of noncultural methods in the diagnosis of invasive aspergillosis in an experimental animal model

In the present study, the value of the molecular method (Real-Time PCR), antigendetection (galactomannan, glucan), and Lysis Centrifugation blood culture system(ISOLATORTM) was investigated in the diagnosis of invasive aspergillosis in the animalmodel. In addition, the determination of tissue chitin levels which was used for theconfirmation of the presence of infection was studied.These tests were studied in the blood (serum, whole blood), BAL fluid, and pulmonarytissue samples of different groups, named Group I as control group, Group II as neutropeniacontrol group, and Group III as aspergillosis group.All of the tests were found negative in Group I and II. A total of 20 of 22 pulmonarytissue samples yielded Aspergillus colonies in the aspergillosis group. There were asignificant difference between Group I and III (p<0.05) in terms of chitin levels of pulmonarytissue samples. A total of 10 rats with aspergillosis were tested using lysis centrifugationculture system and no growth was detected in any specimen. Aspergillus DNA was detectedin 7 of 12 BAL fluid samples (58.3%), 7 of 19 blood samples (36.8%), and 4 of 22 pulmonarytissue samples (%18) using Real-Time PCR method. Galactomannan antigen was detected in7 of 20 serum samples (35%) using Platelia® Aspergillus Galactomannan ELISA Assay.Quantitative detection of β-glucan levels were investigated by using FungitellTM assay inserum and bronchoalveolar lavage fluid samples. It was found to be positive in 11 of 22 serumsamples (%50) and 9 of 17 BAL fluid samples (%52.9).In conclusion, none of the non-culture-based diagnostic tests were shown as adequatein the diagnosis of invasive aspergillosis, individually. The confused nature of themicroorganism and the aspergillosis is related to the variability of the performance of non-culture-based diagnostic methods as reported in the literature.The blood samples were evaluated as the most valuable clinical sample for thescreening of suspected patients. Therefore, there will be no need for other invasive diagnosticmethods such as biopsy. Future clinical studies are required for comparing the performance ofthe different non-culture based diagnostic methods and the optimal integration aproaches ofthem.