Antifungal activity of sustainable histone deacetylase inhibitors against planktonic cells and biofilms of Candida spp. and Cryptococcusneoformans.

The limited therapeutic options for fungal infections and the increased incidence of fungal strains resistant to antifungal drugs, especially Candida spp., require the development of new antifungal drugs and strategies. Histone deacetylase inhibitors (HDACi), like vorinostat, have been studied in cancer treatment and have antifungal effects, acting alone or synergistically with classical antifungals. Here we investigated the antifungal activity of two novel sustainable HDACi (LDT compounds) based on vorinostat structure. Molecular docking simulation studies reveal that LDT compounds can bind to Class-I HDACs of Candida albicans, C. tropicalis, and Cryptococcus neoformans, which showed similar binding mode to vorinostat. LDT compounds showed moderate activity when tested alone against fungi but act synergistically with antifungal azoles against Candida spp. They reduced biofilm formation by more than 50% in C. albicans (4 µg/mL), with the main action in fungal filamentation. Cytotoxicity of the LDT compounds against RAW264.7 cells was evaluated and LDT536 demonstrated cytotoxicity only at the concentration of 200 µmol/L, while LDT537 showed IC50 values of 29.12 µmol/L. Our data indicated that these sustainable and inexpensive HDACi have potential antifungal and antibiofilm activities, with better results than vorinostat, although further studies are necessary to better understand the mechanism against fungal cells.

Fungal infections are neglected diseases that affect more than a billion people worldwide. Some histone deacetylase inhibitors can act against fungal cells. Our data reveal that HDACi LDT536 and LDT537 have potential antibiofilm and antifungal activities.

Biofilm formation on cat claws by Sporothrix species: An ex vivo model.

This work aimed to evaluate the ability of Sporothrix species to attach and form biofilm on the surface of cat claws as an ex vivo model. A total of 14 strains (5 Sporothrix brasiliensis, 3 Sporothrix schenckii s. str., 3 Sporothrix globosa and 3 Sporothrix mexicana) were used. The biofilms were incubated for periods of 01, 03, 07, 10 and fifteenth 15 days. Their metabolic activities were evaluated by the XTT reduction assay and the morphology and structure were investigated by scanning electron microscopy (SEM). The analysis of the SEM images revealed that all the species can form biofilms on cat claws. The metabolic activity in the ex vivo biofilms was similar to that found in in vitro biofilms when incubated for the same period. This is the first report of an ex vivo biofilm model involving cat claws. The ability to form biofilms on cat claws can increase the viable period of the fungus and consequently the number of possibly infected animals and people.

Antifungal activity of deferiprone and EDTA against Sporothrix spp.: Effect on planktonic growth and biofilm formation.

The present study evaluated the antifungal activity of the chelators deferiprone (DFP) and ethylenediaminetetraacetic acid (EDTA) and their effect on biofilm formation of the S. schenckii complex. Eighteen strains of Sporothrix spp. (seven S. brasiliensis, three S. globosa, three S. mexicana and five Sporothrix schenckii sensu stricto) were used. Minimum inhibitory concentration (MIC) values for EDTA and DFP against filamentous forms of Sporothrix spp. ranged from 32 to 128 µg/ml. For antifungal drugs, MIC values ranged from 0.25 to 4 µg/ml for amphotericin B, from 0.25 to 4 µg/ml for itraconazole, and from 0.03 to 0.25 µg/ml for terbinafine. The chelators caused inhibition of Sporothrix spp. in yeast form at concentrations ranging from 16 to 64 µg/ml (for EDTA) and 8 to 32 µg/ml (for DFP). For antifungal drugs, MIC values observed against the yeast varied from 0.03 to 0.5 µg/ml for AMB, 0.03 to 1 µg/ml for ITC, and 0.03 to 0.13 µg/ml for TRB. Both DFP and EDTA presented synergistic interaction with antifungals against Sporothrix spp. in both filamentous and yeast form. Biofilms formed in the presence of the chelators (512 µg/ml) showed a reduction of 47% in biomass and 45% in metabolic activity. Our data reveal that DFP and EDTA reduced the growth of planktonic cells of Sporothrix spp., had synergistic interaction with antifungal drugs against this pathogen, and reduced biofilm formation of Sporothrix spp. LAY SUMMARY: Our data reveal that iron chelators deferiprone and ethylenediaminetetraacetic acid reduced the growth of planktonic cells of Sporothrix spp. as well as had synergistic interaction with antifungal drugs against this pathogen and reduced biofilm formation of Sporothrix spp.

Exogenous fungal quorum sensing molecules inhibit planktonic cell growth and modulate filamentation and biofilm formation in the Sporothrix schenckii complex.

This study investigated the effect of the quorum sensing molecules (QSMs) farnesol, 2-phenylehtanol, tyrosol and tryptophol against planktonic cells, filamentation and biofilms of Sporothrix spp. The antifungal activity of QSMs was evaluated by broth microdilution. QSMs showed MICs in the ranges of 0.01-1 µM (farnesol), 1-8 mM (2-phenylehtanol and tyrosol), and >16 mM (tryptophol). Filamentous biofilm formation was inhibited by farnesol and 2-phenylehtanol and stimulated by tyrosol. Yeast biofilm formation was inhibited by 2-phenylehtanol and tyrosol. Tryptophol did not affect Sporothrix biofilm formation. QSMs showed MICs against mature biofilms of 8-32 µM (farnesol), 8-32 mM (2-phenylehtanol) and 64-128 mM (tyrosol). In conclusion, farnesol, 2-phenylethanol and tyrosol have antifungal activity against planktonic and sessile cells and modulate filamentation and biofilm formation in Sporothrix spp.

Effect of proton pump inhibitors on susceptibility and melanogenesis of Sporothrix species.

Introduction. Sporotrichosis is a subcutaneous infection caused by dimorphic Sporothrix species embedded in the clinical clade. Fungi have virulence factors, such as biofilm and melanin production, which contribute to their survival and are related to the increase in the number of cases of therapeutic failure, making it necessary to search for new options.Gap statement. Proton pump inhibitors (PPIs) have already been shown to inhibit the growth and melanogenesis of other fungi.Aim. Therefore, this study aimed to evaluate the effect of the PPIs omeprazole (OMP), rabeprazole (RBP), esomeprazole, pantoprazole and lansoprazole on the susceptibility and melanogenesis of Sporothrix species, and their interactions with itraconazole, terbinafine and amphotericin B.Methodology. The antifungal activity of PPIs was evaluated using the microdilution method, and the combination of PPIs with itraconazole, terbinafine and amphotericin B was assessed using the checkerboard method. The assessment of melanogenesis inhibition was assessed using grey scale.Results. The OMP and RBP showed significant MIC results ranging from 32 to 256 µg ml-1 and 32 to 128 µg ml-1, respectively. Biofilms were sensitive, with a significant reduction (P<0.05) in metabolic activity of 52% for OMP and 50% for RBP at a concentration of 512 µg ml-1 and of biomass by 53% for OMP and 51% for RBP at concentrations of 512 µg ml-1. As for the inhibition of melanogenesis, only OMP showed inhibition, with a 54% reduction.Conclusion. It concludes that the PPIs OMP and RBP have antifungal activity in vitro against planktonic cells and biofilms of Sporothrix species and that, in addition, OMP can inhibit the melanization process in Sporothrix species.

Antifungal Activity of Chitosan against Histoplasma capsulatum in Planktonic and Biofilm Forms: A Therapeutic Strategy in the Future?

Histoplasmosis is a respiratory disease caused by Histoplasma capsulatum, a dimorphic fungus, with high mortality and morbidity rates, especially in immunocompromised patients. Considering the small existing therapeutic arsenal, new treatment approaches are still required. Chitosan, a linear polysaccharide obtained from partial chitin deacetylation, has anti-inflammatory, antimicrobial, biocompatibility, biodegradability, and non-toxicity properties. Chitosan with different deacetylation degrees and molecular weights has been explored as a potential agent against fungal pathogens. In this study, the chitosan antifungal activity against H. capsulatum was evaluated using the broth microdilution assay, obtaining minimum inhibitory concentrations (MIC) ranging from 32 to 128 µg/mL in the filamentous phase and 8 to 64 µg/mL in the yeast phase. Chitosan combined with classical antifungal drugs showed a synergic effect, reducing chitosan's MICs by 32 times, demonstrating that there were no antagonistic interactions relating to any of the strains tested. A synergism between chitosan and amphotericin B or itraconazole was detected in the yeast-like form for all strains tested. For H. capsulatum biofilms, chitosan reduced biomass and metabolic activity by about 40% at 512 µg/mL. In conclusion, studying chitosan as a therapeutic strategy against Histoplasma capsulatum is promising, mainly considering its numerous possible applications, including its combination with other compounds.

Perfil epidemiológico de Staphylococcus spp. isolados de hemoculturas de pacientes internados em um hospital de atenção terciária da rede pública do Ceará / Epidemiological profile of Staphylococcus spp. isolated from hemocultures of interned patients in a tertiary attention hospital of the Ceará public network

Staphylococcus spp. vem ganhando destaque em infecções na corrente sanguínea (ICS), apresentando alta prevalência, multirresistência e considerável poder de letalidade. O presente estudo teve como objetivo analisar a prevalência e traçar o perfil de sensibilidade das espécies de Staphylococcus spp. isoladas de amostras de hemoculturas positivas obtidas de um hospital de atenção terciária da rede pública do Ceará, no período de janeiro de 2015 a dezembro de 2018. Dos 3292 exames de hemocultura realizados, apenas 15,88% tiveram resultado positivo, dos quais 24,85% eram cocos Gram positivos. S. aureus representou 1,53% das hemoculturas positivas com 50% das cepas resistentes à oxacilina. Os isolados de Staphylococcus sp. coagulase negativo obtiveram prevalência de 10,89%, representados por: S. epidermidis (n=23), S. haemolyticus (n=17), S. hominis (n=13), S. saprophyticus (n=2) e S. warneri (n=2). Verificou-se multirresistência em diversos isolados analisados, apresentando variações intra e interespécies. Portanto, nossos achados melhoram o entendimento da epidemiologia das ICS causadas por Staphylococcus spp., na instituição de estudo, bem como seu perfil de sensibilidade. A identificação precoce do agente infeccioso auxilia na escolha adequada do tratamento, aumentando as chances de cura e reduzindo o tempo de internação do paciente. (AU)

Staphylococcus spp. has been highlighted among bloodstream infections (BI), presenting high prevalence, multidrug resistance and considerable lethality. The present study aimed to analyze the prevalence and the susceptibility profile of Staphylococcus spp. isolated from positive blood cultures from a tertiary care public hospital of Ceará, from January 2015 to December 2018. Of the 3292 blood cultures performed during this period, only 15.88% were positive, of which 24.85% were Gram positive cocci. S. aureus represented 1.53% of positive blood cultures, of which 50% were oxacilin resistant. Isolates of coagulase-negative Staphylococcus spp. showed a prevalence of 10.89%, represented by: S. epidermidis (n = 23), S. haemolyticus (n = 17), S. hominis (n = 13), S. saprophyticus (n = 2) and S. warneri (n = 2). Multiresistance occurrence was verified in several of the analyzed isolates, presenting intra and inters species variations. Therefore, our findings improve the understanding of the epidemiology of BI caused by Staphylococcus spp. in the studied institution, as well as its susceptibility profile. Early identification of the infectious agent might aid in the appropriate choice of treatment, increasing the chance of cure and reducing the patient length stay in hospital. (AU)