Aspergillus Fungemia Versus Pseudofungemia: A Case Series Illustrating Diagnostic Criteria, Risk Factors, and Clinical Implications

Aspergillus species are environmental fungi that can cause invasive disease in susceptible hosts. Detection in blood cultures is uncommon and may represent true fungemia or pseudofungemia. Previously, Aspergillus fungemia was primarily described in patients with hematologic malignancies and transplant recipients, but it is becoming a more common cause of infection as diverse at-risk patient populations emerge. In this case series, we describe two patients with positive blood cultures for Aspergillus. The first is a 52-year-old man with metastatic colorectal cancer and multiple risk factors who developed confirmed Aspergillus terreus fungemia. The second is a 77-year-old man with chronic myelomonocytic leukemia following allogeneic stem cell transplantation in whom a single blood culture yielded Aspergillus without clinical evidence of invasive infection, consistent with pseudofungemia. Distinguishing true fungemia from contamination is critical. Corticosteroid use, intravascular devices, and environmental exposures may predispose even non-neutropenic individuals to invasive disease. Early recognition and targeted antifungal therapy are essential, given the significant associated mortality.