Environmental monitoring for filamentous fungal pathogens in hematopoietic cell transplant units

Abstract

The incidence of invasive fungal disease (IFD) is on the rise due to increasing numbers of highly immunocompromized patients. Nosocomial IFD remains common despite our better understanding of its risk factors and pathophysiology. High-efficiency particulate air filtration with or without laminar air flow, frequent air exchanges, a positive pressure care environment, and environmental hygiene, amongst other measures, have been shown to reduce the mould burden in the patient environment. Environmental monitoring for moulds in areas where high-risk patients are cared for, such as hematopoietic cell transplant units, has been considered an adjunct to other routine environmental precautions. As a collaborative effort between authors affiliated to the Infection Prevention and Control Working Group and the Fungal Infection Working Group of the International Society of Antimicrobial Chemotherapy (ISAC), we reviewed the English language literature and international guidance to describe the evidence behind the need for environmental monitoring for filamentous fungi as a quality assurance approach with an emphasis on required additional precautions during periods of construction. Many different clinical sampling approaches have been described for air, water, and surface sampling with significant variation in laboratory methodologies between reports. Importantly, there are no agreed-upon thresholds that correlate with an increase in the clinical risk of mould infections. We highlight important areas for future research to assure a safe environment for highly immunocompromized patients.

Keywords: air sampling; environmental monitoring; invasive fungal infection; nosocomial aspergillosis.