Detection of human pathogenic Fusarium species in hospital and communal sink biofilms by using a highly specific monoclonal antibody Marwan Al-Maqtoofi 1,2 and Christopher R. Thornton 1 * 1 Biosciences, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK. 2 University of Basrah, College of Science, Biology Department, Basrah, Iraq. Summary The fungus Fusarium is well known as a plant pathogen, but has recently emerged as an oppor- tunistic pathogen of humans. Habitats providing direct human exposure to infectious propagules are largely unknown, but there is growing evidence that plumbing systems are sources of human path- ogenic strains in the Fusarium solani species complex (FSSC) and Fusarium oxysporum species complex (FOSC), the most common groups infect- ing humans. Here, a newly developed Fusarium- specific monoclonal antibody (mAb ED7) was used to track FSSC and FOSC strains in sink drain biofilms by detecting its target antigen, an extrac- ellular 200 kDa carbohydrate, in saline swabs. The antigen was detectable in 52% of swab sam- ples collected from sinks across a University campus and a tertiary care hospital. The mAb was 100% accurate in detecting FSSC, FOSC, and F. dimerum species complex (FDSC) strains that were present, as mixed fungal communities, in 83% of sink drain biofilms. Specificity of the ELISA was confirmed by sequencing of the internally tran- scribed spacer 1 (ITS1)-5.8S-ITS2 rRNA-encoding regions of culturable yeasts and molds that were recovered using mycological culture, while transla- tion elongation factor (TEF)-1a analysis of Fusarium isolates included FSSC 1-a, FOSC 33, and FDSC ET-gr, the most common clinical patho- types in each group. Introduction Species in the fungal genus Fusarium are ubiquitous environmental molds, and pathogens of both plants and animals (Zhang et al., 2006; Thornton and Wills, 2015). In immunocompromised humans, such as patients with hematological malignancies and hematopoietic stem cell and solid organ transplant recipients, Fusarium species are significant emerging pathogens, causing a frequently fatal disseminated disease known as fusariosis with an associated mortality rate of 50%–75% (Boutati and Anaissie, 1997; Girmenia et al., 2000; Musa et al., 2000; Dignani and Anaissie, 2004; Jensen et al., 2004; Nucci and Anaissie, 2007). In some tertiary cancer cen- ters, Fusarium has emerged as the second most common mold pathogen after Aspergillus (Walsh and Groll, 1999; Muhammed et al., 2011). Regardless of human immune status, Fusarium species can cause localized nail infections (onychomycosis) (Arrese et al., 1996), bone and joint infections (Koehler et al., 2014), infections of burn wounds (Latenser, 2003), skin infec- tions (Nucci and Anaissie, 2002; Gurusidappa and Mamatha, 2011) and are the most frequent cause of mycotic eye infections known as fungal keratitis (Jurkunas et al., 2009), leading to progressive corneal destruction and endophthalmitis, with loss of vision or even loss of the affected eye (Dursun et al., 2003; Edelstein et al., 2012). A recent multistate outbreak of fungal keratitis in the United States and in Singapore and Hong Kong was asso- ciated with contact lens solution contaminated with multiple strains of Fusarium and which led to visual loss in many patients and the need for corneal transplantation (Chang et al., 2006). While such outbreaks are rare, disse- minated Fusarium infections and keratomycoses have increased in frequency over the past decade (Koehler et al., 2014) and an increasing body of evidence suggests that the main environmental sources of human pathogenic Fusarium species are contaminated water systems (Doggett, 2000; Anaissie et al., 2002; Mehl and Epstein, 2008; Anaissie et al., 2011). A number of studies have recovered pathogenic Fusarium species from plumbing fix- tures and it is hypothesized that microbial biofilms on Received 3 November, 2015; accepted 15 January, 2016. *For correspondence: E-mail C.R.Thornton@ex.ac.uk; Tel. 144 (0)1392 725172; Fax 144 (0)1392 263434. V C 2016 Society for Applied Microbiology and John Wiley & Sons Ltd Environmental Microbiology (2016) 00(00), 00–00 doi:10.1111/1462-2920.13233