Investigating the Presence of Aspergillus fumigatus and A. flavus Using Galactomannan Enzyme Assay and TaqMan Real-Time PCR Technique

Invasive aspergillosis (IA), a serious and fatal disease, is caused by numerous opportunistic fungi including Aspergillus species. Lack of early diagnosis and delay in treatment lead to the rapid spread of the infection and relapse, increase treatment costs, and ultimately cause death.
This study aimed at investigating the presence of Aspergillus species by Galactomannan EIA (GM) and TaqMan q PCR methods.
Fluid samples of bronchoalveolar lavage (BAL) were collected from 89 patients, who were at risk for IA and underwent a bronchoscopy at Shariati hospital in Tehran, Iran. The specimens were examined using direct examination, culture methods, and GM and TaqMan real-time PCR.
A total of 23 samples were found to be positive in direct examination, 7 were identified as Aspergillus fumigatus, and 11 were positive as A. flavus in culture assays, 27 were GM positive, and 29 were positive with PAN Aspergillus probe. Moreover, 7 samples were positive with A. fumigatus probe and 11 were positive with A. flavus probe. Negative predictive value (NPV), sensitivity, positive predictive value (PPV), and specificity for a ≥ 1.0 BAL GM level were 98.4%, 94.4%, 62.9%, and 85.9%, respectively, and were 100% for TaqMan Real time PCR.
Our findings revealed that TaqMan real- time PCR has a great value for detection of Aspergillus species in BAL specimen. Since early diagnosis has been highly considered to prevent the occurrence of drug resistance and mortality rate, it is necessary to use this method directly to detect Aspergillus species in BAL or blood specimens without culture. On the other hand, Galactomannan assay with a 98.4% NPV could be used to screen the patients with suspected invasive aspergillosis. Additionally, due to the lack of need for specialized devices, an appropriate diagnostic technique should be used in laboratories that do not have access to specialized procedures.