RESUMO
In immunocompetent individuals, Fusarium spp. stands out as the causative agent of onychomycosis, among the non-dermatophyte molds. Despite evidence indicating that Fusarium oxysporum organizes itself in the form of a biofilm causing onychomycosis, there is little literature on the etiopathogenesis of the biofilm on the nail, specifically the signaling molecules present, known as quorum sensing (QS). Thus, this study detected the presence of a molecule related to QS from the ex vivo biofilm of F. oxysporum on human nail and investigated its effect on preformed biofilm in vitro. The detection and physicochemical characterization of a QS molecule, from the extracellular matrix (ECM), was carried out by Fourier transform infrared (FTIR) spectroscopy with an attenuated total reflectance (ATR) accessory and by headspace gas chromatography coupled to mass spectrometry (GC-MS) analyses. Determination of viable cells, cell activity, total biomass, ECM components and scanning electron microscopy (SEM) were performed to evaluate the influence of the QS molecule on the in vitro biofilm of F. oxysporum. The beginning, in the ex vivo biofilm of F. oxysporum on human nails, the volatile organic compound 2-ethyl-1-hexanol (2EH) was detected as a component of QS. Thereafter in vitro analyses, synthetic 2EH was able to modulate the biofilm by stimulating its filament, increasing total biomass and ECM production in terms of total carbohydrates, but with a reduction in total proteins and nucleic acids. We thus evidence, for the first time, the presence of 2EH in the biofilm of F. oxysporum, developed on the human nail, and the in vitro action of this compound as a QS molecule.
RESUMO
Onychomycosis is a chronic fungal nail infection caused by several filamentous and yeast-like fungi, such as the genus Candida spp., of great clinical importance. Black yeasts, such as Exophiala dermatitidis, a closely related Candida spp. species, also act as opportunistic pathogens. Fungi infectious diseases are affected by organisms organized in biofilm in onychomycosis, making treatment even more difficult. This study aimed to evaluate the in vitro susceptibility profile to propolis extract and the ability to form a simple and mixed biofilm of two yeasts isolated from the same onychomycosis infection. The yeasts isolated from a patient with onychomycosis were identified as Candida parapsilosis sensu stricto and Exophiala dermatitidis. Both yeasts were able to form simple and mixed (in combination) biofilms. Notably, C. parapsilosis prevailed when presented in combination. The susceptibility profile of propolis extract showed action against E. dermatitidis and C. parapsilosis in planktonic form, but when the yeasts were in mixed biofilm, we only observed action against E. dermatitidis, until total eradication.
RESUMO
Fusarium keratoplasticum is a common specie in human infections and is responsible for many diseases affecting immunocompetent and immunocompromised patients. This study aimed to evaluate the ability of Fusarium keratoplasticum to form biofilm in venous catheters (VC), focusing on the development of maturation and dispersion over time (24, 48, 72, 96 and 120 h) and the evaluation amphotericin B (AB) susceptibility in planktonic cells and after 96 h of biofilm formation. F. keratoplasticum was able to form a biofilm in VC with maturation most likely between 48 and 72 h, according to colony count and total biomass results. The dispersion process supposedly occurred from 72 to 96 h, when we observed a decrease in the parameter's colony count, total biomass and mitochondrial metabolic activity. The planktonic cells of F. keratoplasticum were susceptible to AB, however, there was no inhibition of the F. keratoplasticum strain biofilm in any of the AB concentrations, with the growth of the fungus recovering after 48 h in contact with AB. Thus, our findings suggest that in addition to forming a biofilm on VC, F. keratoplasticum becomes AB-resistant, highlighting the concern of this fungus on medical devices.