Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 4 2026 08 04 615 620 Arun Sachu Department of Microbiology, Believers Church Medical College, Thiruvalla, Kerala, India Alice David Department of Biostatistics, Believers Church Medical College, Thiruvalla, Kerala, India 2025 11 15 2026 05 27 Background and Objectives: In most laboratories, diagnosis of invasive aspergillosis (IA) depends on culture and histopathological examination of the involved tissues. Galactomannan (GM) is a polysaccharide antigen detectable in body fluids and represents an ideal assay for diagnosing invasive pulmonary aspergillosis. The main objectives of this study were to estimate the proportion of patients with proven, probable, and possible aspergillosis and to compare different diagnostic methods. Materials and Methods: Samples for culture, microscopy, and GM assay were taken from a total of 60 patients. The enrolled patients were divided into proven, probable, and possible aspergillosis groups. Results: Among the 60 patients in the study, there were 9 (15%) cases of probable aspergillosis. galactomannan assay was positive in 19 patients. Galactomannan assay had a higher sensitivity (66.7%) when compared to other fungal assays for diagnosing probable aspergillosis. Conclusion: Diagnosing invasive aspergillosis is extremely challenging, and biomarkers such as galactomannan assay are important for early diagnosis. Raising the cutoff to >1 can eliminate false-positive results associated with the GM assay. https://ijm.tums.ac.ir/index.php/ijm/article/view/5932 https://ijm.tums.ac.ir/index.php/ijm/article/download/5932/1921