Utility of BAL Galactomannan testing: A prospective analytical study

Abstract

Introduction: Galactomannan (GM) is a component of Aspergillus cell wall. The usefulness of GM levels in body fluids is still unclear. We evaluated the utility of Bronchoalveolar Lavage (BAL) GM testing in patients with suspected pulmonary Aspergillosis. Aims and Objectives: To assess the utility of BAL Galactomannan assay in diagnosis of pulmonary Aspergillus infections Methods: 90 consecutive patients with suspicion of pulmonary Aspergillosis, based on pre-defined clinic-radiological parameters, were included in our study. BAL samples obtained via fibre optic bronchoscopy were tested for routine microbiology and Galactomannan(GM). Data was collected and multivariate analysis done. Results: 50 patients (55.56 %) were found to have BAL GM >0.8, a cut off considered as positive. 13 samples were fungal smear/fungal culture positive for Aspergillus spp. and BAL GM was positive in 11 of these samples (84.62%; p=0.04794) with a mean GM of 1.65. 39 patients with negative fungal smear/culture but BAL GM positive (mean GM=0.97) were also prescribed systemic anti-fungal drugs and clinico-radiological improvement was seen in these patients. BAL GM was positive in 18 of 20 patients with bronchiectasis (90%; p=0.0011) and in up to 65 % patients with asthma or COPD. Smoking history or biomass fuel exposure also showed a trend towards positivity with BAL GM value. Conclusion: In patients with suspicion of pulmonary Aspergillosis, BAL galactomannan level was found to be a better marker than fungal smear/culture. While microbiological and histopathological evidences are gold standard to diagnose fungal infections, our study shows that in patients with negative fungal smear or culture, BAL Galactomannan can be conclusive for diagnosis.