P408 Evaluation of fungal serum biomarkers in the diagnosis and for monitoring patients with post tuberculosis chronic pulmonary aspergillosis

Abstract

Abstract Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Objectives The evaluation of serum β-D-glucan, galactomannan, and Aspergillus fumigatus specific IgG in the diagnosis and clinical management of patients with chronic pulmonary aspergillosis. Methods Consecutive patients with a past history of pulmonary tuberculosis (PTB) with clinical suspicion of chronic pulmonary aspergillosis (CPA) attending the outpatient services of PGIMER, Chandigarh were included from August 2019 to August 2021, and CPA was defined as described by Denning et al. including both radiological and mycological evidence. Age and sex-matched post-PTB individuals selected from a population attending the chest clinic were enrolled as controls. Serum samples were obtained from all participants and testing for serum β-D-glucan (Fungitell, CapeCod), galactomannan (Platelia, BioRad) and Aspergillus fumigatus specific IgG (ImmunoCAP, Phadia) was performed as per manufacturer's instructions. Results A total of 105 post-TB patients with CPA and 11 controls were enrolled. Aspergillus fumigatus (n = 8) was the most commonly isolated species, followed by A. flavus (n = 4), and A. niger (n = 2). The mean A. fumigatus specific IgG levels, serum galactomannan index and BDG levels were higher among CPA cases vs. controls at 101.4 mgA/l vs. 11.8 mgA/l, P-value: .0001; 0.73 vs. 0.35, P-value: .3134; and 133.7 pg/ml vs. 32.37 pg/ml, P-value: .012, respectively (Figs. 1a, b, c). The serum BDG had an area under curve 0.834 ± 0.044 (95% CI: 0.748-0.920) on the ROC curve with a sensitivity of 57.1% and specificity of 100% at the kit cut-off of 80 pg/ml (Fig. 2a). Comparison between CPA patients with multiple (n = 38) versus single lobe (n = 67) involvement showed comparable A. fumigatus specific IgG levels (112.3 vs. 93.8; P-value: .133 respectively) while galactomannan index and BDG levels were higher in cases with multiple vs. single lobe involvement (0.94 vs. 0.57, P-value: .117), and (174.3 vs. 105.3, P-value: .0071), respectively (Fig. 1d, e, f). There was a significant association of BDG value with the severity of dyspnea (P-value: .002) and a trend of higher A. fumigatus specific IgG was also seen to correlate with the severity of dyspnea (Fig. 2b and 2c). Conclusion BDG assay can serve as an adjunct in the diagnosis of patients with CPA. An association of higher levels of BDG with multiple lobe involvement and severe dyspnea could be due to more extensive tissue damage associated with a greater release of antigen in circulation during progressive disease. More studies with a larger number of control samples, preferably with multi-center coordination can further improve our understanding of this test's applicability in routine practice.