Abstract
ObjectiveTrichosporon asahii is the major causative fungus of disseminated or deep-seated trichosporonosis and forms a biofilm on medical devices. Biofilm formation leads to antifungal drug resistance, so biofilm-related infections are relatively difficult to treat and infected devices often require surgical removal. Therefore, prevention of biofilm formation is important in clinical settings. In this study, to identify metal cations that affect biofilm formation, we evaluated the effects of cation chelators on biofilm formation in T. asahii.ResultsWe evaluated the effect of cation chelators on biofilm formation, since microorganisms must assimilate essential nutrients from their hosts to form and maintain biofilms. The inhibition by N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) was greater than those by other cation chelators, such as deferoxamine, triethylenetetramine, and ethylenediaminetetraacetic acid. The inhibitory effect of TPEN was suppressed by the addition of zinc. TPEN also inhibited T. asahii hyphal formation, which is related to biofilm formation, and the inhibition was suppressed by the addition of zinc. These results suggest that zinc is essential for biofilm formation and hyphal formation. Thus, zinc chelators have the potential to be developed into a new treatment for biofilm-related infection caused by T. asahii.
Highlights
Pathogenic microorganisms adapt to host environments and cause various infectious diseases
We evaluated the effect of cation chelators on biofilm formation, since microorganisms must assimilate essential nutrients from their hosts to form and maintain biofilms
TPEN inhibited T. asahii hyphal formation, which is related to biofilm formation, and the inhibition was suppressed by the addition of zinc
Summary
We tested whether biofilm formation by T. asahii was inhibited by the cation chelators TPEN, DFO, TETA, and EDTA. TPEN, EDTA, and TETA reduced biofilm formation in a concentration-dependent manner (Fig. 1). IC50 values (the concentration of a compound required for the half inhibition of biofilm formation) of TPEN, TETA, and EDTA were 0.17 μM, 117 μM, and 47 μM, respectively. TPEN was the most effective cation chelator to inhibit biofilm formation by T. asahii. TPEN has been used as a zinc chelator in several studies [15–17]. In the presence of 0.1 μM TPEN, hyphal formation decreased, whereas zinc addition induced hyphal elongation (Fig. 3). These results suggest that zinc regulated hyphal formation of T. asahii
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