Fungal infections in patients with haematological malignancies in the pre-triazole era: the dawn of a new era in medical mycology.

Background: Opportunistic invasive fungal infections (IFIs) emerged as common causes of death of patients with haematological malignancies (HM) once effective antibacterial therapy reduced bacterial deaths. In the dawn of medical mycology, timely diagnosis was difficult, and treatment was limited by the toxicity of antifungals and associated with poor outcomes.

Objectives: This study aims to chronicle key diagnostic and therapeutic milestones before triazoles and show how they forged the foundations of modern mycology practice in HM.

Sources: Autopsy series, clinical trials, pharmacological studies, and historical commentaries augmented by seminal reviews on chemotherapy, haematopoietic cell transplantation and antifungal development.

Content: Autopsy studies identified the importance of Candida, Aspergillus and Mucorales and linked prolonged neutropenia and corticosteroids to heightened risk of infection. Computed tomography and early galactomannan assays improved early diagnosis, whereas trials of empirical amphotericin B in persistent neutropenic fever halved mortality. Adjunctive strategies, including protected environments, gut decontamination, cytokine therapy and granulocyte transfusions, were often constrained by cost, toxicity, or uncertain benefit. Historically, the azole era began with ketoconazole and progressed to itraconazole and fluconazole, broadening prophylaxis but selecting for rare moulds and resistant yeasts. These pressures drove the development of potent newer triazoles and echinocandins and introduced risk-adapted prophylactic strategies.

Implications: Lessons from the pre-triazole era endure: host immunity remains the prime determinant of IFI risk and outcome; timely, sensitive diagnostics are lifesaving; and antifungal stewardship must anticipate the evolution of fungal resistance. As novel chemotherapeutics, cellular therapies, and resistant pathogens reshape IFI epidemiology in HM, continuous innovations in diagnostics, antifungals, and immunomodulatory approaches remain essential.