Diagnostic Value of Galactomannan Enzyme Immunoassay Compared to Conventional Modalities in Bronchoalveolar Lavage of Immunocompromised Patients

Introduction: Aspergillus fumigatus is the leading cause of Invasive Aspergillosis (IA) worldwide. Diagnosing IA can be challenging due to difficulties in sample collection and the limited sensitivity and specificity of culture-based methods, often leading to delayed diagnosis and increased morbidity. Galactomannan (GM) testing, an antigen released by Aspergillus during infection, offers a valuable alternative. Detection of GM, along with other diagnostic criteria, can facilitate quicker identification of IA, reducing turnaround times and improving patient management. Methods: A prospective study was conducted over four months in the Mycology Laboratory of a tertiary care hospital in Delhi. A total of 45 Bronchoalveolar Lavage (BAL) samples were collected from immunocompromised patients at the Delhi State Cancer Institute. Conventional diagnostic methods, including Gram staining, KOH mount, India ink staining, and culture, were performed, along with the XEMA GalMAg EIA for the detection of GM antigen. The results obtained were compared and analyzed. Results: GM was detected in 4 out of 45 samples (8.88%), while 3 other samples yielded equivocal results in the ELISA. Of these seven samples, three demonstrated bacterial and yeast growth in culture, with findings consistent with Gram stain results. We found that 6.7% (3/45) of patients had a history of chemotherapy, 8.9% (4/45) presented with respiratory symptoms, and 8.9% (4/45) exhibited systemic signs. CT scan findings showed multiple nodular lesions in the lung fields in 8.9% (4/45) of cases. Lymphocytopenia was observed in the absence of neutropenia. Discussion: Detecting GM antigen in BAL samples may help in the early diagnosis of IA in cancer patients, especially those undergoing chemotherapy. Although GM testing showed limited positive results in this small group, it can still be a useful tool when combined with clinical and radiological findings, but further follow-up and confirmatory tests are needed to improve diagnostic accuracy. Conclusion: The detection of GM, along with other clinical and radiological findings, aids in the early identification of IA, potentially improving patient outcomes by reducing diagnostic delays.