http://repositorio.ufc.br/handle/riufc/56326 Thu, 11 Jun 2026 19:42:57 GMT 2026-06-11T19:42:57Z http://repositorio.ufc.br/handle/riufc/86337 Título: Avaliação da atividade antimicrobiana da hidralazina frente a Staphylococcus aureus e Candida spp Autor(es): Nascimento, Francisca Bruna Stefany Aires do Abstract: It is estimated that infectious diseases are the leading cause of death worldwide, responsible for approximately 13 million deaths each year. Staphylococcus aureus and Candida spp are among the main human pathogens, related to several infections with different levels of severity. Available treatments are increasingly limited. S. aureus has several virulence factors, in addition to easily acquiring resistance mechanisms. While Candida spp. mainly affects immunocompromised patients, has a small available pharmacological treatment arsenal and is affected by the toxicity fact. The new antimicrobials development is a global urgency and drugs repurposing is the fastest, most economical and safest mechanism. This study aimed to evaluate the antimicrobial activity of hydralazine, in vitro, against clinical strains of S. aureus and Candida spp biofilms, and to evaluate, in silico, the possible action mechanism. By microdilution in broth, the hydralazine minimum inhibitory concentration was determined, which was on average 256 µg/ml against S. aureus. In the tolerance assessment, hydralazine proved to be bactericidal and the association with oxacillin and vancomycin was synergistic in 50 and 25% of the strains, respectively. In evaluating the cell viability of biofilms formed by S. aureus by reducing Methylthiazolyldiphenyltetrazolium bromide (MTT), the sessile minimum inhibitory concentration (50%) ranged from 256 to 2048 µg/ml. Analysis of cell viability by propidium iodide exclusion showed that hydralazine increased non-viable cells (58.78%). In the Comet and TUNEL assays, it was possible to detect breaks and the fragmentation presence in the S. aureus DNA strands. In silico, hydralazine demonstrated greater affinity and the possibility of forming lower energy complexes with the targets S. aureus gyrase complex with DNA (-7.6 kcal/mol), S. aureus gyrase (-7.3 kcal/mol) and S. aureus TyrRS (-7.5 kcal/mol). Biofilms of Candida albicans, C. parapsilosis and C. tropicalis were treated with hydralazine, itraconazole and a combination of these drugs. Reduction in cell viability was assessed by MTT metabolization. Hydralazine (10xMIC) significantly (p≤0.05) reduced the biofilms formed viability. The biofilm formation inhibition was more effective and the MIC of hydralazine for each strain was able to significantly (p≤0.05) reduce biofilm viability. In scanning electron microscopy images, it is possible to see Candida albicans cells damaged by hydralazine. In in silico assays, hydralazine demonstrates more favorable binding energy with targets Exo-B-(1,3)-glucanase (-7.1 kcal/mol) and CYP51 (-7.2 kcal/mol). Therefore, it is concluded that hydralazine has potential to be redirected to the treatment of infections caused by S. aureus and Candida spp., in association with current drugs or alone, acting on planktonic cells and also on biofilms. Tipo: Tese Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86337 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85991 Título: Efeito antifúngico do anlodipino em cepas de Candida spp. e em biofilmes mistos com Staphylococcus aureus resistente à meticilina (SARM): avaliação in vitro Autor(es): Queiroz, Helaine Almeida Abstract: Antimicrobial resistance (AMR) has become one of the main threats to global public health, driven by the excessive and inappropriate use of antimicrobials , which favors the emergence and spread of multidrug-resistant strains. In this context, invasive fungal infections caused by Candida yeasts have become a growing problem, with candidemia associated with high mor-tality rates (30-40%). Simultaneously, Methicillin-Resistant Staphylococcus aureus (MRSA) remains an important bacterial pathogen, responsible for infections ranging from skin condi-tions to potentially fatal situations. The management of these infections is even more challen-ging due to the ability of these microorganisms to form biofilms, communities adhered to sur-faces, which offer significant protection and confer antimicrobial tolerance up to a thousand times greater than in planktonic cells. Medical devices, widely used in clinical procedures, re-present environments conducive to the formation of these biofilms, especially when there is colonization by Candida spp. and MRSA. The objective of this study was to investigate the antifungal activity of amlodipine against Candida spp. strains in planktonic and biofilm forms, to elucidate its possible mechanism of action, and to evaluate its effect on mixed biofilms of Candida spp. and MRSA, both in 96-well polystyrene plates and in Peripheral Venous Cathe-ters (PVCs). To this, an Antifungal Susceptibility Test was performed to determine the Mi-nimum Inhibitory Concentrations (MICs). The action of amlodipine against Candida spp. and Candida spp. plus MRSA biofilms was determined by the MTT assay, and its possible me-chanism of action was investigated through flow cytometry tests. The results demonstrated that amlodipine exhibited Minimum Inhibitory Concentrations (MICs) ranging from 62.5 to 250μg/mL, as well as significant action on mature and pre-formed and forming biofilms, promoting reductions between 50% and 90%. Additionally, the drug increased phosphatidyl-serine externalization and reduced fungal cell viability, suggesting induction of apoptosis. It was also observed that amlodipine reduced metabolic viability by approximately 90% in “in vitro’ polymicrobial biofilms at a concentration equivalent to 8xMIC (1000-2000 μg/mL), in all combinations tested, as well as exerting a potent action on mixed biofilms in CVPs, with a reduction in the number of colonies between 60% and 90%. Furthermore, the morphology was evaluated by light microscopy, confirmed by Scanning Electron Microscopy (SEM). Ba-sed on these findings, amlodipine emerges as a potential candidate for the treatment of fungal and mixed infections. However, additional in vivo studies are needed to validate and expand these results Tipo: Tese Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85991 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85848 Título: Vigilância em saúde única da resistência a antifúngicos e a compostos de amônio quaternário em Candida spp. no Ceará e busca por alternativa terapêutica Autor(es): Brasil, Jaiane Alves Abstract: From a One Health perspective, tackling antifungal resistance in Candida spp. requires an understanding of multiple factors, such as interaction with environments and chemical agents. Furthermore, drug repositioning and combination therapy are strategies to overcome therapeutic failures. This study aimed to isolate and identify Candida spp. from human clinical samples (n=59), hospital surfaces (n=25), production animals (n=107), and the environment of these animals (n=9); analyze the sensitivity profile to the antifungals FLC, MCF, and AMB; and the effect of benzalkonium chloride (BZ) and didecyl dimethyl ammonium chloride (DDAC) against isolates in planktonic and biofilm forms, as well as evaluate the effect of deferiprone (DEF), an iron chelator, on Candida spp. in planktonic and biofilm forms, isolated and in combination with the antifungals fluconazole (FLC), amphotericin B (AMB), and caspofungin (CAS). Finally, it was evaluated whether the inhibition of the fungus by DFP was reversed with ferrous sulfate (FeSO₄). Sensitivity to antifungals, quaternary ammonium compounds, and deferiprone was analyzed according to document m27-a3. The checkerboard method was used to evaluate the interaction between deferiprone and the antifungals. The antibiofilm activity of the antifungals, ammonium compounds, and deferiprone was evaluated by MTT reduction and biomass quantification by crystal violet. 109 Candida spp. yeasts were isolated. FLC showed variable MIC, from 0.125 to 64 µg/ml for isolates of human origin; 0.5 to 4 µg/ml for isolates from hospital environments; 0.125 to 64 µg/ml for isolates of animal origin, and 1 to 32 µg/ml for isolates from animal environments. MICs for MCF ranged from 0.0625 to 0.5 µg/ml for isolates of human origin; 0.0625 to 1 µg/ml for isolates from hospital environments; 0.0625 to 0.1 µg/ml for isolates of animal origin, and 0.03 µg/ml for isolates from animal environments. AMB exhibited MICs of 0.031 to 1 µg/ml for isolates of human origin; 0.125 to 0.5 µg/ml for isolates from hospital environments; 0.031 to 1 µg/ml for isolates of animal origin, and 0.06 and 0.25 µg/ml for isolates from animal environments. DDA showed MICs between 0.0625 and 1 µg/mL, and BZ showed MICs ranging from 0.0625–4 µg/mL. Forming and mature Candida spp. biofilms showed a significant reduction in metabolic activity and biomass after exposure to BZ and DDA. DEF showed MICs ranging from 16 to 1024 µg/mL against the tested isolates. In the checkerboard assay, DEF reduced the MICs of FLC, AMB, and CAS by up to 8, 32, and 64 times, respectively, against the planktonic form. In the MTT assay, DEF caused an increase in the metabolic activity of forming biofilms of C. tropicalis and C. glabrata; and a tendency towards reduced metabolic activity of mature Candida spp. biofilms (n=12) at 1024 µg/mL. Crystal violet analysis revealed an increase in the biomass of forming C. parapsilosis biofilms when treated with DEF; and a tendency towards a reduction in mature Candida spp. biofilms (n=12) at concentrations of 256 to 1024 µg/mL and 2 to 32 µg/mL, when compared to drug-free controls. Supplementation with (FeSO₄) reduced the antifungal efficacy of DEF against planktonic Candida spp. DEF demonstrated antifungal activity and synergism with FLC, AMB, and CAS against Candida spp., with greater efficacy observed against C. glabrata. Furthermore, DEF significantly influenced biofilm formation, showing a species-dependent effect. However, its effectiveness was significantly reduced by supplementation with FeSO₄, demonstrating that it acts directly on iron balance for Candida spp. Tipo: Tese Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85848 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85535 Título: Perfil clínico-epidemiológico das infecções causadas por Trichosporon spp. em um hospital pediátrico de referência e busca de novas estratégias de controle do crescimento fúngico Autor(es): Silva, Bruno Nascimento da Abstract: Invasive fungal infections (IFIs) involve contamination of the bloodstream and invasion of sterile tissues and/or organs and are considered highly relevant public health issues due to high morbidity and mortality rates. Trichosporon spp. are considered opportunistic fungi, as they take advantage of microbial dysbiosis and host immune imbalance to cause serious invasive infections. This study investigated the clinical and epidemiological profile of invasive infections by Trichosporon spp., as well as the impact of calcineurin and Hsp90 protein inhibition on the growth of this pathogen. The epidemiological study included 28 isolates of interest. Data from these patients were collected and analyzed regarding: age, sex, most prevalent species of the genus, distribution by hospital unit, reasons for care, use of invasive devices, clinical specimens from which pathogens were isolated, use of antimicrobials and other conditioning drugs, co-infection, and treatment measures – all of which were associated with the clinical outcome (discharge or death). The strains isolated and selected in the prospective phase (n=12) were studied for their ability to form biofilms and their sensitivity profile to amphotericin B (AMB), voriconazole (VRZ), and fluconazole (FLZ). The second phase of the work concerns the inhibition of calcineurin by the use of Cyclosporine A (CsA), against planktonic cells and biofilms of Trichosporon spp. strains in n=13 already contained in stock. These biofilms were formed in the presence of CsA at concentrations of 25 µg/mL, 50 µg/mL, and 100 µg/mL for the planktonic state and 50 µg/mL and 100 µg/mL for the biofilms. Subsequently, CsA at the same concentrations mentioned above were associated with the antifungals AMB (10 µg/mL), VRZ (50 µg/mL), and FLZ (64 µg/mL) and subjected to the same tests. The impact of CsA on the ultrastructure of the biofilms was evaluated by Scanning Electron Microscopy (SEM) both in isolation and in combination with the antifungals. Bioinformatics analyses were performed to investigate the antibiofilm potential caused by calcineurin inhibition in T. asahii. In the inhibition of Hsp90 using Radicicol (RAD), the strains were subjected to planktonic sensitivity testing and subsequently studied with mature biofilms (48h) exposed to RAD at concentrations of 6.25 µg/mL for T. asahii and 10 µg/mL for T. inkin. Then, the same concentrations of RAD in the mature biofilms were associated with AMB 4 µg/mL for T. asahii and 2 µg/mL for T. inkin and VRZ 0.125 µg/mL for an additional 24h in contact with the mature biofilm in vitro, the morphology of the biofilms was assessed by SEM, and virulence was evaluated using an experimental infection model with Galleria mellonella larvae. The epidemiological study showed that the most affected pediatric population over the years were boys, most of whom were admitted to Intensive Care Units (ICUs). Patients with neurological diseases and cancer; those using various invasive medical devices, such as feeding tubes; most samples isolated from urine; a significant portion used prophylactic antimicrobials; mortality rates are considerable; the most prevalent species is T. asahii; the strains obtained are capable of forming biofilms. CsA and RAD, isolated and in combination with antifungals, are able to inhibit the fungal growth of T. inkin and T. asahii in vitro and significantly alter the ultrastructure of biofilms. RAD is effective in treating infected G. mellonella larvae. These results suggest new and promising therapeutic targets for invasive trichosporonosis, considering the difficulty and resistance in treating these infections Tipo: Tese Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85535 2025-01-01T00:00:00Z