High Rate of Exophiala dermatitidis Recovery in the Airways of Patients with Cystic Fibrosis Is Associated with Pancreatic Insufficiency

Abstract

The black-pigmented fungus Exophiala dermatitidis is considered to be a harmless colonizer of the airways of cystic fibrosis (CF) patients. The aim of this study was to establish the recovery rate of E. dermatitidis in respiratory specimens from CF patients, transplant recipients, and subjects with other respiratory disorders in Sweden. Second, we wished to determine if particular clinical traits were associated with E. dermatitidis colonization of the airways and the antifungal susceptibility profiles of Exophiala strains. Sputum and bronchoalveolar lavage samples (n ‫؍‬ 492) derived from 275 patients were investigated. E. dermatitidis was isolated in respiratory specimens from 19% (18/97) of the CF patients but in none of the other patient categories. All isolates were recovered after 6 to 25 days of incubation on erythritol-chloramphenicol agar (ECA) medium. Morphological and genetic analyses confirmed species identity. Pancreatic insufficiency was positively associated with the presence of E. dermatitidis in sputum samples (P ‫؍‬ 0.0198). Antifungal susceptibility tests demonstrated that voriconazole and posaconazole had the lowest MICs against E. dermatitidis. In conclusion, E. dermatitidis is a frequent colonizer of the respiratory tract in CF patients in Sweden and appears to be associated with more advanced disease. Whether E. dermatitidis is pathogenic remains to be elucidated.

Molecular typing and antifungal susceptibility of Exophiala isolates from patients with cystic fibrosis

“…Most of the isolates of E. dermatitidis and E. phaeomuriformis displayed very low MICs of amphotericin B, itraconazole and voriconazole, thus, confirming previous observations from other reports (Kondori et al, 2011;Badali et al, 2011;Fothergill et al, 2009). However, in patient UCL1, 10 out of the 12 sequential isolates showed high MICs (between 4 and 16 mg ml 21 ) of voriconazole, and 11 isolates showed MICs of 2 mg ml 21 of amphotericin B.…”

Black Yeasts and Their Filamentous Relatives: Principles of Pathogenesis and Host Defense

“…Low concentrations of salt stimulate production of muriform cells in various pathogenic agents of chromoblastomycosis (79). Slightly raised salt levels determine the occurrence of Exophiala dermatitidis in the lungs of patients with cystic fibrosis (80,81). On the other hand, high concentrations of iron increase siderophore production in tissues.…”

Fungal Biofilms in Human Disease

“…and Exophiala spp. have been isolated from different cohorts of CF patients (Blyth et al 2010 ;Cimon et al 2000 ;Kondori et al 2011 ). Given the ubiquitous nature of moulds within the environment, and with thousands of conidia being inhaled every day (Richardson 2009 ), it is unsurprising that pathogenic fungi can adhere, colonise and form complex multispecies biofi lms in lungs with abnormal clearance mechanisms such as CF however their pathogenic role has not yet been fully elucidated.…”