Development of in-house ELISA for Scedosporium/Lomentospora serodiagnosis.

Scedosporium/Lomentospora species are ubiquitous molds that can cause deep-seated infections and allergic bronchopulmonary mycoses (ABPM). Serodiagnosis is currently performed by immunoprecipitation techniques (IP), which are time-consuming and lack reproducibility. In addition, as antigenic extracts for these fungi are not commercially available, many centers stopped performing this analysis. Therefore, there is a need for automated quantitative alternatives, such as ELISA. The aim of this study was to develop an ELISA for serodiagnosis of Scedosporium/Lomentospora infections. All sera received for Scedosporium/Lomentospora serodiagnosis expertise from April 2022 to February 2024 were tested in parallel using IP and an in-house ELISA with antigenic extracts from both S. apiospermum and L. prolificans. Clinical and biological data such as positive culture, total IgE level and final diagnosis retained were also collected prospectively. The concordance between techniques was calculated, with chi² tests performed to investigate the correlation between ELISA and culture results or final diagnosis. We tested 58 serum samples from 41 different patients. The concordance between IP and ELISA was 64% for S. apiospermum and 62% for L. prolificans. ELISA results obtained with S. apiospermum antigen extract were significantly correlated with culture results (p < 0.001, chi² test). ELISA was also more effective than IP to diagnose ABPM. The Scedosporium/Lomentospora ELISA gave satisfactory results, particularly for S. apiospermum. Further validation on a larger cohort is required implementing this ELISA for routine practice instead of IP. In addition, studies should be conducted on purified native proteins or combination with recombinant antigens to improve standardization.