Drain outlets in patient rooms as sources for invasive fusariosis: an analysis of patients with haematological disorders

J Hosp Infect. 2020 Apr 28;S0195-6701(20)30204-8. doi: 10.1016/j.jhin.2020.04.029. Online ahead of print.


Background: Invasive fusariosis (IF) is a frequently fatal disease as there are few antifungals to treat it, making the prevention of IF crucial. However, fusarium infections have not been as thoroughly studied as other common pathogenic fungi such as Aspergillus or Candida.

Aim: To investigate the epidemiology of IF in patients with haematological diseases in Japan and to elucidate the infectious route of fusarium infection.

Methods: We retrospectively analysed 29 IF cases in patients with haematological diseases from 2009 to 2019 in Japan. To discover the infectious source of IF, we performed an indoor environment survey targeted at indoor air and drain outlets in medical institutions and residences using culture-based and metagenomic methods. Finally, we performed aerosol- and droplet-mediated dispersion studies.

Findings: The epidemiological study showed that the primary pathogen of IF was Fusarium solani species complex (FSSC), and the most common species was Fusarium petroliphilum. Most patients were likely to develop IF during hospitalization. A fusarium culture was positive in 26 of 72 drain samples. Few fusarium were detected from air samples; by contrast, 29 of 108 isolates from the drain outlets were identified as fusarium. Furthermore, similar results were obtained in the metagenomic analysis. Interestingly, species belonging to FSSC were isolated from indoor drain outlets, which was similar to those of the IF patients. In the droplet-mediated dispersion study, eight to 17 colonies of fusarium were isolated.

Conclusion: Our study indicates that causative Fusarium spp. could inhabit drain outlets in hospitals or residences, and droplet-mediated fusarium dispersion is a potential cause of IF.

Keywords: Drain outlets; Droplet-mediated fusarium dispersion; Fusarium; Invasive fusariosis.