Background: Scopulariopsis/Microascus is a rare but devastating pathogen due to its intrinsic resistance to nearly all available antifungal agents. Microascus gracilis, an ascomycetous mold in the order Microascales, family Microascaceae, have recently emerged as significant invasive pathogens causing opportunistic infections.
Objectives and Methods: We present a case of pleural infection caused by M.gracilis in an immunocompromised man. In order to further understand the characteristics of the pathogen isolated from the patient, we identified the strain through mycological characteristics, matrix-assisted laser desorption/ionization(MALDI) time-of-flight(TOF) mass spectrometry (MALDI-TOF MS) and internal transcribed spacer (ITS)-based sequencing, performed in vitro drug susceptibility testing against common antifungal agents. Moreover, we assessed the lymphocyte subsets and programmed cell death protein 1(PD-1) expression in peripheral blood and pleural effusion to monitor the efficacy of therapy with thymosin-α-1 and intravenous immunoglobulin.
Results: Filamentous fungi isolated from chest tube and pleural fluid were identified as M.gracilis based on classical morphology, mass spectrometry and molecular biology methods. The susceptibility results in vitro revealed that multiple antifungal agents were inactive against the strain. The adjuvant immunomodulatory treatment successfully upgraded the level of CD3+T and CD4+T cells, while downgraded the level of CD3+PD-1+T and CD4+PD-1+T cells both in peripheral blood and pleural effusion.
Conclusions: The immunocompromised host with opportunistic M.gracilis infection, rapid and accurate recognize thorough direct microscopic testing with calcofluor white and MOLDI-TOF MS is the key to achieve definite diagnosis, and a combination of antifungal therapy with immunomodulatory therapy is vital for improving survival.