Synergistic activity of gold nanoparticles with amphotericin B on persister cells of Candida tropicalis biofilms.

AIM: The antifungal activity was studied on sessile and persister cells (PCs) of Candida tropicalis biofilms of gold nanoparticles (AuNPs) stabilized with cetyltrimethylammonium bromide (CTAB-AuNPs) and those conjugated with cysteine, in combination with Amphotericin B (AmB). MATERIALS/METHODS: The PC model was used and synergistic activity was tested by the checkerboard assay. Biofilms were studied by crystal violet and scanning electron microscopy. RESULTS/CONCLUSIONS: After the combination of both AuNPs and AmB the biofilm biomass was reduced, with significant differences in architecture being observed with a reduced biofilm matrix. In addition, the CTAB-AuNPs-AmB combination significantly reduced PCs. Understanding how these AuNPs aid in the fight against biofilms and the development of new approaches to eradicate PCs has relevance for chronic infection treatment.

Combination of metagenomic next-generation sequencing and conventional tests unraveled pathogen profiles in infected patients undergoing allogeneic hematopoietic stem cell transplantation in Jilin Province of China.

Background: Infection is the main cause of death for patients after allogeneic hematopoietic stem cell transplantation (HSCT). However, pathogen profiles still have not been reported in detail due to their heterogeneity caused by geographic region. Objective: To evaluate the performance of metagenomic next-generation sequencing (mNGS) and summarize regional pathogen profiles of infected patients after HSCT. Methods: From February 2021 to August 2022, 64 patients, admitted to the Department of Hematology of The First Hospital of Jilin University for HSCT and diagnosed as suspected infections, were retrospectively enrolled. Results: A total of 38 patients were diagnosed as having infections, including bloodstream (n =17), pulmonary (n =16), central nervous system (CNS) (n =4), and chest (n =1) infections. Human betaherpesvirus 5 (CMV) was the most common pathogen in both bloodstream (n =10) and pulmonary (n =8) infections, while CNS (n =2) and chest (n =1) infections were mainly caused by Human gammaherpesvirus 4 (EBV). For bloodstream infection, Mycobacterium tuberculosis complex (n =3), Staphylococcus epidermidis (n =1), and Candida tropicalis (n =1) were also diagnosed as causative pathogens. Furthermore, mNGS combined with conventional tests can identify more causative pathogens with high sensitivity of 82.9% (95% CI 70.4-95.3%), and the total coincidence rate can reach up to 76.7% (95% CI 64.1-89.4%). Conclusions: Our findings emphasized the importance of mNGS in diagnosing, managing, and ruling out infections, and an era of more rapid, independent, and impartial diagnosis of infections after HSCT can be expected.

A potent candicidal peptide designed based on an encrypted peptide from a proteinase inhibitor.

Antimicrobial peptides (AMP) represent an alternative in the treatment of fungal infections associated with countless deaths. Here, we report a new AMP, named KWI-19, which was designed based on a peptide encrypted in the sequence of an Inga laurina Kunitz-type inhibitor (ILTI). KWI-19 inhibited the growth of Candida species and acted as a fungicidal agent from 2.5 to 20 µmol L-1, also showing synergistic activity with amphotericin B. Kinetic assays showed that KWI-19 killed Candida tropicalis cells within 60 min. We also report the membrane-associated mechanisms of action of KWI-19 and its interaction with ergosterol. KWI-19 was also characterized as a potent antibiofilm peptide, with activity against C. tropicalis. Finally, non-toxicity was reported against Galleria mellonella larvae, thus strengthening the interest in all the bioactivities mentioned above. This study extends our knowledge on how AMPs can be engineered from peptides encrypted in larger proteins and their potential as candicidal agents.

Isolation and characterization of Candida tropicalis B: a promising yeast strain for biodegradation of petroleum oil in marine environments.

The increasing interest in environmental protection laws has compelled companies to regulate the disposal of waste organic materials. Despite efforts to explore alternative energy sources, the world remains heavily dependent on crude petroleum oil and its derivatives. The expansion of the petroleum industry has significant implications for human and environmental well-being. Bioremediation, employing living microorganisms, presents a promising approach to mitigate the harmful effects of organic hydrocarbons derived from petroleum. This study aimed to isolate and purify local yeast strains from oil-contaminated marine water samples capable of aerobically degrading crude petroleum oils and utilizing them as sole carbon and energy sources. One yeast strain (isolate B) identified as Candida tropicalis demonstrated high potential for biodegrading petroleum oil in seawater. Physiological characterization revealed the strain's ability to thrive across a wide pH range (4-11) with optimal growth at pH 4, as well as tolerate salt concentrations ranging from 1 to 12%. The presence of glucose and yeast extract in the growth medium significantly enhanced the strain's biomass formation and biodegradation capacity. Scanning electron microscopy indicated that the yeast cell diameter varied based on the medium composition, further emphasizing the importance of organic nitrogenous sources for initial growth. Furthermore, the yeast strain exhibited remarkable capabilities in degrading various aliphatic and aromatic hydrocarbons, with a notable preference for naphthalene and phenol at 500 and 1000 mg/l, naphthalene removal reached 97.4% and 98.6%, and phenol removal reached 79.48% and 52.79%, respectively. Optimization experiments using multi-factorial sequential designs highlighted the influential role of oil concentration on the bioremediation efficiency of Candida tropicalis strain B. Moreover, immobilized yeast cells on thin wood chips demonstrated enhanced crude oil degradation compared to thick wood chips, likely due to increased surface area for cell attachment. These findings contribute to our understanding of the potential of Candida tropicalis for petroleum oil bioremediation in marine environments, paving the way for sustainable approaches to address oil pollution.

Computer-made peptide RQ18 acts as a dual antifungal and antibiofilm peptide though membrane-associated mechanisms of action.

The spread of fungi resistant to conventional drugs has become a threatening problem. In this context, antimicrobial peptides (AMPs) have been considered as one of the main alternatives for controlling fungal infections. Here, we report the antifungal and antibiofilm activity and some clues about peptide RQ18's mechanism of action against Candida and Cryptococcus. This peptide inhibited yeast growth from 2.5 µM and killed all Candida tropicalis cells within 2 h incubation. Moreover, it showed a synergistic effect with antifungal agent the amphotericin b. RQ18 reduced biofilm formation and promoted C. tropicalis mature biofilms eradication. RQ18's mechanism of action involves fungal cell membrane damage, which was confirmed by the results of RQ18 in the presence of free ergosterol in the medium and fluorescence microscopy by Sytox green. No toxic effects were observed in murine macrophage cell lines and Galleria mellonella larvae, suggesting fungal target selectivity. Therefore, peptide RQ18 represents a promising strategy as a dual antifungal and antibiofilm agent that contributes to infection control without damaging mammalian cells.

Bioinspired peptides induce different cell death mechanisms against opportunistic yeasts.

The management of fungal diseases imposes an urgent need for the development of effective antifungal drugs. Among new drug candidates are the antimicrobial peptides, and especially their derivatives. Here, we investigated the molecular mechanism of action of three bioinspired peptides against the opportunistic yeasts Candida tropicalis and Candida albicans. We assessed morphological changes, mitochondrial functionality, chromatin condensation, ROS production, activation of metacaspases, and the occurrence of cell death. Our results indicated that the peptides induced sharply contrasting death kinetics, of 6 h for RR and 3 h for D-RR to C. tropicalis and 1 h for WR to C. albicans. Both peptide-treated yeasts exhibited increased ROS levels, mitochondrial hyperpolarization, cell size reduction, and chromatin condensation. RR and WR induced necrosis in C. tropicalis and C. albicans, but not D-RR in C. tropicalis. The antioxidant ascorbic acid reverted the toxic effect of RR and D-RR, but not WR, suggesting that instead of ROS there is a second signal triggered that leads to yeast death. Our data suggest that RR induced a regulated accidental cell death in C. tropicalis, D-RR induced a programmed cell death metacaspase-independent in C. tropicalis, while WR induced an accidental cell death in C. albicans. Our results were obtained with the LD100 and within the time that the peptides induce the yeast death. Within this temporal frame, our results allow us to gain clarity on the events triggered by the peptide-cell interaction and their temporal order, providing a better understanding of the death process induced by them.

Comparative in vitro analysis of the antifungal activity of different calcium silicate-based endodontic sealers

Aim: This study aimed to perform an in vitro comparative analysis of the antifungal activity of different calcium silicate-based endodontic sealers against three fungal species. Methods: The antifungal properties of three calcium silicate-based sealers were tested: Bio-C Sealer, Cambiar a Sealer Plus BC, and MTA-Fillapex. Two commonly used sealers were used as controls: AH Plus and Endomethasone. An agar diffusion test was performed to analyze the antifungal activity of the sealers against Candida albicans, Candida glabrata, Candida tropicalis, and a mixed microbial culture medium. The results were analyzed using ANOVA (p <0.05). Results: Endomethasone exhibited the highest inhibition against all strains examined, maintaining a consistent level of inhibition throughout 7 days. MTA-Fillapex demonstrated the best performance among the calcium silicate-based sealers for the three fungal species (p < 0.05), maintaining stable values over the 7 days, surpassing that of Endomethasone. Nevertheless, MTA-Fillapex only exhibited antimicrobial effect against the mixed culture for the first 24 hours, and no antimicrobial activity was observed at 48 hours, being surpassed by all tested sealers (p < 0.05). Conclusion: Of all silicate-based sealers tested, only MTA-Fillapex exhibited promising antifungal activity. Nevertheless, care must be taken when extrapolating these results, as MTA-Fillapex exhibited poor antimicrobial activity when tested in mixed microbial cultures

ROS mediated anticandidal efficacy of 3-Bromopyruvate prevents vulvovaginal candidiasis in mice model.

Candidal infections, particularly vulvovaginal candidiasis (VVC), necessitate effective therapeutic interventions in clinical settings owing to their intricate clinical nature and elusive understanding of their etiological mechanisms. Given the challenges in developing effective antifungal therapies, the strategy of repurposing existing pharmaceuticals has emerged as a promising approach to combat drug-resistant fungi. In this regard, the current study investigates molecular insights on the anti-candidal efficacy of a well-proven anticancer small molecule -3-bromopyruvate (3BP) against three clinically significant VVC causing Candida species viz., C. albicans, C. tropicalis and C. glabrata. Furthermore, the study validates 3BP's therapeutic application by developing it as a vaginal cream for the treatment of VVC. 3BP exhibited phenomenal antifungal efficacy (killing >99%) with minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC) of 256 µg/mL against all tested Candida spp. Time killing kinetics experiment revealed 20 min as the minimum time required for 3BP at 2XMIC to achieve complete-killing (99.9%) in all Candida strains. Moreover, the ergosterol or sorbitol experiment explicated that the antifungal activity of 3BP does not stem from targeting the cell wall or the membrane component ergosterol. Instead, 3BP was observed to instigate a sequence of pre-apoptotic cascade events, such as phosphatidylserine (PS) externalization, nuclear condensation and ROS accumulations, as evidenced by PI, DAPI and DCFH-DA staining methods. Furthermore, 3BP demonstrated a remarkable efficacy in eradicating mature biofilms of Candida spp., achieving a maximum eradication level of 90%. Toxicity/safety profiling in both in vitro erythrocyte lysis and in vivo Galleria mellonella survival assay authenticated the non-toxic nature of 3BP up to 512 µg/mL. Finally, a vaginal cream formulated with 3BP was found to be effective in VVC-induced female mice model, as it significantly decreasing fungal load and protecting vaginal mucosa. Concomitantly, the present study serves as a clear demonstration of antifungal mechanistic action of anticancer drug -3BP, against Candida species. This finding holds significant potential for mitigating candidal infections, particularly VVC, within healthcare environments.

Perspective on receptor-associated immune response to Candida albicans single and mixed infections: Implications for therapeutics in oropharyngeal candidiasis.

Oropharyngeal candidiasis (OPC), commonly known as 'thrush', is an oral infection that usually dismantles oral mucosal integrity and malfunctions local innate and adaptive immunities in compromised individuals. The major pathogen responsible for the occurrence and progression of OPC is the dimorphic opportunistic commensal Candida albicans. However, the incidence induced by non-albicans Candida species including C. glabrata, C. tropicalis, C. dubliniensis, C. parapsilosis, and C. krusei are increasing in company with several oral bacteria, such as Streptococcus mutans, S. gordonii, S. epidermidis, and S. aureus. In this review, the microbiological and infection features of C. albicans and its co-contributors in the pathogenesis of OPC are outlined. Since the invasion and concomitant immune response lie firstly on the recognition of oral pathogens through diverse cellular surface receptors, we subsequently emphasize the roles of epidermal growth factor receptor, ephrin-type receptor 2, human epidermal growth factor receptor 2, and aryl hydrocarbon receptor located on oral epithelial cells to delineate the underlying mechanism by which host immune recognition to oral pathogens is mediated. Based on these observations, the therapeutic approaches to OPC comprising conventional and non-conventional antifungal agents, fungal vaccines, cytokine and antibody therapies, and antimicrobial peptide therapy are finally overviewed. In the face of newly emerging life-threatening microbes (C. auris and SARS-CoV-2), risks (biofilm formation and interconnected translocation among diverse organs), and complicated clinical settings (HIV and oropharyngeal cancer), the research on OPC is still a challenging task.

This review aims to discuss the roles of Candida albicans single- and co-infections with non-albicans Candida species or oral bacteria as well as the receptor-mediated immune response in the pathogenesis of oropharyngeal candidiasis (OPC). Current therapeutic approaches are also emphasized for OPC treatment.

Ascending renal infection following experimental candiduria by Candida tropicalis in immunocompromised mice.

The present study evaluated renal infection resulting from the implantation of C. tropicalis in the bladder of immunosuppressed mice. Yeasts were implanted in two manners: planktonic and via preformed biofilm on a small catheter fragment (SCF). Renal histopathology and cultures was performed 72 and 144 h after cystotomy was carried out in mice from three groups: group I contained non-contaminated mice implanted with a sterile SCF; group II mice received a sterile SCF plus a yeast suspension containing 1 × 107 yeasts/mL in a planktonic form; group III mice were implanted with a SCF containing preformed C. tropicalis biofilm. Viable yeasts were found in the kidneys of mice from both groups II and III. However, after 72 h the planktonic cells (group II) invaded more quickly than the sessile cells (group III). Over a longer period (144 h), group III exhibited a more invasive infection (50% of the animals presented renal infection and the renal fungal load was 3.2 log10 CFU/g tissue) than in group II, where yeasts were not found. C. tropicalis introduced into the bladder in two ways (in planktonic or biofilm form) were able to reach the kidney and establish a renal fungal infection, causing interstitial disorders. The data of the present study therefore support the hypothesis of an ascending pathway for renal infections by C. tropicalis. Furthermore, the biofilm resulted in a greater and progressive risk of renal infection, attributed to the slow detachment of the yeasts.

Expression of ERG11, ERG3, MDR1 and CDR1 genes in Candida tropicalis / Expresión de los genes ERG11, ERG3, MDR1 y CDR1 en Candida tropicalis

Introduction. Drug resistance to azoles is a growing problem in the Candida genus. Objective. To analyze molecularly the genes responsible for fluconazole resistance in Candida tropicalis strains. Materials and methods. Nineteen strains, with and without exposure to fluconazole, were selected for this study. The expression of MDR1, CDR1, ERG11, and ERG3 genes was analyzed in sensitive, dose-dependent sensitive, and resistant strains exposed to different concentrations of the antifungal drug. Results. MDR1, ERG11 and ERG3 genes were significantly overexpressed in the different sensitivity groups. CDR1 gene expression was not statistically significant among the studied groups. Seven of the eight fluconazole-resistant strains showed overexpression of one or more of the analyzed genes. In some dose-dependent sensitive strains, we found overexpression of CDR1, ERG11, and ERG3. Conclusion. The frequency of overexpression of ERG11 and ERG3 genes indicates that they are related to resistance. However, the finding of dose-dependent resistant/sensitive strains without overexpression of these genes suggests that they are not exclusive to this phenomenon. More basic research is needed to study other potentially involved genes in the resistance mechanism to fluconazole.

Introducción. La farmacorresistencia a los azoles es un problema creciente en el género Candida. Objetivo. Analizar molecularmente los genes responsables de la resistencia a fluconazol en cepas de Candida tropicalis. Materiales y métodos. Para este estudio, se seleccionaron 19 cepas, con exposición a fluconazol y sin ella. Se analizó la expresión de los genes MDR1, CDR1, ERG11 y ERG3 en cepas sensibles, sensibles dependiente de la dosis, y resistentes, previamente expuestas a diferentes concentraciones del fármaco antifúngico. Resultados. Se encontró que los genes MDR1, ERG11 y ERG3 estaban significativamente sobreexpresados en los diferentes grupos de sensibilidad. La expresión del gen CDR1 no fue estadísticamente significativa entre los grupos estudiados. Siete de las ocho cepas resistentes a fluconazol mostraron sobreexpresión de uno o más de los genes analizados. En algunas cepas sensibles dependientes de la dosis, se encontró sobreexpresión de CDR1, ERG11 y ERG3. Conclusión. La sobreexpresión de los genes ERG11 y ERG3 indica que están relacionados con la resistencia de las cepas de Candida. Sin embargo, el hallazgo de cepas resistentes o sensibles según la dosis, sin sobreexpresión de estos genes, sugiere que pueden existir otros genes involucrados en este fenómeno. Se necesitan más investigaciones básicas que contribuyan al estudio de otros genes potencialmente involucrados en el mecanismo de resistencia al fluconazol.

Epidemiology and Outcomes of Non-albicans Candida Bloodstream Infections in Transplant Recipients and Cancer Patients.

We performed a retrospective survey of non-Candida albicans candidemia in patients with cancer, including those with solid tumors and those with hematological malignancies as well as transplants patients both, solid-organ transplant recipients and hematopoietic stem cell transplant recipients. The study was performed at two healthcare centers in New York City and covered the years 2018-2022. A total of 292 patients (318 isolates) were included in the study. In order of frequency, C. glabrata (38%) was the most common species recovered, followed by C. parapsilosis (19.2%), C. tropicalis (12.6%), C. krusei (10.7%), C. lusitaniae (5.7%), and C. guilliermondii (4.4%). Micafungin was the most common antifungal treatment and 18.5% of patients were on antifungal prophylaxis. The 30-day crude mortality was 40%. 4.5% of patients had more than one non-albicans species detected. In conclusion, this study represents one of the largest surveys of non-albicans species in cancer and transplant patients and provides data on the current epidemiology of these Candida species in this patient population.

Mortalidad de la sepsis en la unidad de cuidados intensivos / Mortality from sepsis in intensive care unit

INTRODUCCIÓN. La sepsis es un estado de disfunción multisistémica, que se produce por una respuesta desregulada del huésped a la infección. Diversos factores influyen en la gravedad, manifestaciones clínicas y progresión de la sepsis, tales como, heterogeneidad inmunológica y regulación dinámica de las vías de señalización celular. La evolución de los pacientes depende del tratamiento oportuno, las escalas de puntuación clínica permiten saber la mortalidad estimada. OBJETIVO. Evaluar la mortalidad en la unidad de cuidados intensivos; establecer el manejo y la utilidad de aplicar paquetes de medidas o "bundlers" para evitar la progresión a disfunción, fallo multiorgánico y muerte. METODOLOGÍA. Modalidad de investigación tipo revisión sistemática. Se realizó una búsqueda bibliográfica en bases de datos como Google académico, Mendeley, ScienceDirect, Pubmed, revistas como New England Journal Medicine, Critical Care, Journal of the American Medical Association, British Medical Journal. Se obtuvo las guías "Sobreviviendo a la sepsis" actualización 2021, 3 guías internacionales, 10 estudios observacionales, 2 estudios multicéntricos, 5 ensayos aleatorizados, 6 revisiones sistémicas, 5 metaanálisis, 1 reporte de caso clínico, 4 artículos con opiniones de expertos y actualizaciones con el tema mortalidad de la sepsis en UCI con un total de 36 artículos científicos. RESULTADOS. La mortalidad de la sepsis en la unidad de cuidados intensivos, fue menor en el hospital oncológico de Guayaquil, seguido de Australia, Alemania, Quito, Francia, Estados Unidos de Norteamérica y Vietnan, La mortalidad más alta se observa en pacientes con enfermedades del tejido conectivo. DISCUSIÓN. La aplicación de los paquetes de medidas o "bundlers" en la sepsis, se asocia con una mejor supervivencia y menores días de estancia hospitalaria. CONCLUSIÓN. Las escalas SOFA, APACHE II y SAPS II ayudan a predecir la mortalidad de forma eficiente, en la detección y el tratamiento temprano en pacientes con enfermedades agudas y de alto riesgo.

INTRODUCTION. Sepsis is a state of multisystem dysfunction, which is caused by a dysregulated host response to infection. Several factors influence the severity, clinical manifestations and progression of sepsis, such as immunological heterogeneity and dynamic regulation of cell signaling pathways. The evolution of patients depends on timely treatment, clinical scoring scales allow to know the estimated mortality. OBJECTIVE. To evaluate mortality in the intensive care unit; to establish the management and usefulness of applying bundlers to prevent progression to dysfunction, multiorgan failure and death. METHODOLOGY. Systematic review type research modality. A bibliographic search was carried out in databases such as Google Scholar, Mendeley, ScienceDirect, Pubmed, journals such as New England Journal Medicine, Critical Care, Journal of the American Medical Association, British Medical Journal. We obtained the guidelines "Surviving Sepsis" update 2021, 3 international guidelines, 10 observational studies, 2 multicenter studies, 5 randomized trials, 6 systemic reviews, 5 meta-analyses, 1 clinical case report, 4 articles with expert opinions and updates on the subject of sepsis mortality in ICU with a total of 36 scientific articles. RESULTS. The mortality of sepsis in the intensive care unit, was lower in the oncological hospital of Guayaquil, followed by Australia, Germany, Quito, France, United States of America and Vietnam, The highest mortality is observed in patients with connective tissue diseases. DISCUSSION. The application of bundlers in sepsis is associated with better survival and shorter days of hospital stay. CONCLUSIONS. The SOFA, APACHE II and SAPS II scales help to predict mortality efficiently in the early detection and treatment of patients with acute and high-risk disease.

Dimorphism of Candida tropicalis and its effect on nitrogen and phosphorus removal and sludge settleability.

Candida tropicalis PNY, a novel dimorphic strain with the capacity of simultaneous carbon, nitrogen and phosphorus removal in anaerobic and aerobic conditions, was isolated from activated sludge. Dimorphism of C. tropicalis PNY had effect on removing nitrogen and phosphorous and slightly affected COD removal under aerobic condition. Sample with high hypha formation rate (40 ± 5%) had more removal efficiencies of NH4+-N (50 mg/L) and PO43--P (10 mg/L), which could achieve 82.19% and 97.53%, respectively. High hypha cells dosage exhibited good settleability and filamentous overgrowth was not observed. According to label-free quantitative proteomics assays. Up-regulated proteins involved in the mitogen-activated protein kinase (MAPK) pathway indicated the active growth and metabolism process of sample with high hypha formation rate (40 ± 5%). And proteins concerning about glutamate synthetase and SPX domain-contain protein explain for the nutrient removal mechanism including assimilation of ammonia and polyphosphates synthesis.

Candida bloodstream infection in patients with cancer: A retrospective analysis of an 11-year period.

BACKGROUND: Candida bloodstream infection (CBSI) is a growing problem among patients with cancer. AIM: To describe the main clinical and microbiological characteristics in patients with cancer who suffer CBSI. METHODS: We reviewed the clinical and microbiological characteristics of all patients with CBSI diagnosed between January 2010 and December 2020, at a tertiary-care oncological hospital. Analysis was done according to the Candida species found. Multivariate logistic regression analysis was used to determine the risk factors associated with 30-day mortality. RESULTS: There were 147 CBSIs diagnosed, 78 (53%) in patients with hematologic malignancies. The main Candida species identified were Candida albicans (n=54), Candida glabrata (n=40) and Candida tropicalis (n=29). C. tropicalis had been mainly isolated from patients with hematologic malignancies (79.3%) who had received chemotherapy recently (82.8%), and in patients with severe neutropenia (79.3%). Seventy-five (51%) patients died within the first 30 days, and the multivariate analysis showed the following risk factors: severe neutropenia, a Karnofsky Performance Scale score under 70, septic shock, and not receiving appropriate antifungal treatment. CONCLUSIONS: Patients with cancer who develop CBSI had a high mortality related with factors associated with their malignancy. Starting an empirical antifungal therapy the soonest is essential to increase the survival in these patients.

Comportamiento de Candida en niños hospitalizados en unidades de cuidados intensivos / Incidence of Candida in children hospitalized in intensive care units

Introducción: La candidemia es considerada el tipo de fungemia más frecuente asociada a pacientes en unidades de cuidados intensivos. Es una afección rápidamente progresiva con elevada mortalidad, la cual presenta dificultad en un diagnóstico precoz y capacidad de resistencia al tratamiento. Objetivos: Caracterizar aspectos epidemiológicos, clínicos y microbiológicos de las especies de Candida aisladas en niños hospitalizados en unidades de cuidados intensivos. Métodos: Se realizó un estudio descriptivo y transversal en 143 aislamientos de especies de Candida obtenidas en hemocultivos de pacientes menores de 18 años, en el laboratorio de Microbiología del Hospital Universitario Ginecobstétrico «Mariana Grajales», en el período de enero de 2009 a diciembre de 2018. Se utilizaron tablas de contingencia (prueba de Ji Cuadrado y V de Cramer); se utilizaron las variables: edad, sexo, factores de riesgo, especies y servicios hospitalarios. Resultados: Los mayores aislamientos de candidemia correspondieron a pacientes del sexo femenino de edades comprendidas entre 29 días y 18 años. Todos fueron sometidos al uso de antimicrobianos y con ventilación mecánica. El mayor número de aislamientos en pacientes de 9 años correspondió a Candida tropicalis, que fue la más aislada en la Unidad de Neonatología y Cuidados Intensivos Pediátricos, no así en Cuidados Intermedios donde predominó Candida sin precisar especie. Por estas razones se puede señalar que existe una relación entre las especies y los servicios hospitalarios. Conclusiones: Predominaron pacientes del sexo femenino mayores de 29 días y hasta 18 años hospitalizados en la Unidad de Cuidados Intensivos Pediátricos; la especie más aislada fue Candida tropicalis.

Introduction: candidemia is considered the most frequent type of fungemia associated with patients hospitalized in intensive care units. It is a rapidly progressive condition with high mortality, difficult to diagnose early and resistant to treatment. Objective: to characterize the epidemiological, clinical and microbiological aspects of Candida species isolated from children hospitalized in intensive care units. Methods: a descriptive and cross-sectional study was carried out on 143 isolates of Candida species corresponding to blood cultures from patients under 18 years of age and obtained in the Microbiology laboratory at "Mariana Grajales" Gynecological and Obstetric University Hospital, from January 2009 to December 2018. Contingency tables were used (Chi- square and Cramer's V tests); age, gender, risk factors, species and hospital services were the used variables. Results: the largest candidemia isolates corresponded to female patients aged between 29 days and 18 years. All were subjected to the use of antimicrobials and mechanical ventilation. The highest number of isolates in 9-year-old patients corresponded to Candida tropicalis, which was the most isolated species in the Neonatology and Pediatric Intensive Care Unit, but not in the Intermediate Care Unit where Candida predominated without specifying the species. For these reasons, it can be pointed out that there is a relationship between species and hospital services. Conclusions: female patients older than 29 days and up to 18 years hospitalized in the Pediatric Intensive Care Unit predominated; the most isolated species was Candida tropicalis.

Alginate oligosaccharides enhance the antifungal activity of nystatin against candidal biofilms.

Background: The increasing prevalence of invasive fungal infections in immuno-compromised patients is a considerable cause of morbidity and mortality. With the rapid emergence of antifungal resistance and an inadequate pipeline of new therapies, novel treatment strategies are now urgently required. Methods: The antifungal activity of the alginate oligosaccharide OligoG in conjunction with nystatin was tested against a range of Candida spp. (C. albicans, C. glabrata, C. parapsilosis, C. auris, C. tropicalis and C. dubliniensis), in both planktonic and biofilm assays, to determine its potential clinical utility to enhance the treatment of candidal infections. The effect of OligoG (0-6%) ± nystatin on Candida spp. was examined in minimum inhibitory concentration (MIC) and growth curve assays. Antifungal effects of OligoG and nystatin treatment on biofilm formation and disruption were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and ATP cellular viability assays. Effects on the cell membrane were determined using permeability assays and transmission electron microscopy (TEM). Results: MIC and growth curve assays demonstrated the synergistic effects of OligoG (0-6%) with nystatin, resulting in an up to 32-fold reduction in MIC, and a significant reduction in the growth of C. parapsilosis and C. auris (minimum significant difference = 0.2 and 0.12 respectively). CLSM and SEM imaging demonstrated that the combination treatment of OligoG (4%) with nystatin (1 µg/ml) resulted in significant inhibition of candidal biofilm formation on glass and clinical grade silicone surfaces (p < 0.001), with increased cell death (p < 0.0001). The ATP biofilm disruption assay demonstrated a significant reduction in cell viability with OligoG (4%) alone and the combined OligoG/nystatin (MIC value) treatment (p < 0.04) for all Candida strains tested. TEM studies revealed the combined OligoG/nystatin treatment induced structural reorganization of the Candida cell membrane, with increased permeability when compared to the untreated control (p < 0.001). Conclusions: Antimicrobial synergy between OligoG and nystatin against Candida spp. highlights the potential utility of this combination therapy in the prevention and topical treatment of candidal biofilm infections, to overcome the inherent tolerance of biofilm structures to antifungal agents.

Rational design, synthesis, antifungal evaluation and docking studies of antifungal peptide CGA-N12 analogues based on the target CtKRE9.

Candida tropicalis is a major non-albicans species that causes invasive candidiasis. CGA-N12, an anti-Candida peptide found by our group, disrupted cell wall architecture by inhibiting the activity of the protein killer-resistant 9 (KRE9), a ß-1,6-glucan synthase specific to Candida spp. and plants. Herein, a set of CGA-N12 analogues were rationally designed based on the interaction networks between CGA-N12 and C. tropicalis KRE9 (CtKRE9). Seven CGA-N12 analogues with significantly improved antifungal activity against C. tropicalis were screened by reducing the docking energy of CGA-N12 and CtKRE9 and increasing the number of positive charges on CGA-N12 based on a stable three-dimensional model of CtKRE9. CGA-N12 and its analogues exhibited antifungal activity against C. tropicalis and its persist cells; they also inhibited biofilm formation and eradicated preformed biofilms. Compared with fluconazole, they displayed higher activities against the growth of persister cells and more effective preformed biofilm eradication. Among them, CGA-N12-0801, CGA-N12-0902 and CGA-N12-1002 displayed much higher activity and anti-proteinase digestion stability than CGA-N12. Specifically, CGA-N12-0801 was the optimal analogue, with a minimum inhibitory concentration of 3.46 µg/mL and a therapeutic index of 158.07. The results of electronic microscopy observations and KRE9 activity inhibition assays showed that CGA-N12 and its analogues killed C. tropicalis by disrupting the architecture of the cell wall and the integrity of the cell membrane. In conclusion, for the first time, we provide a simple and reliable method for the rational design of antimicrobial peptides and ideal candidates for treating Candida infections that not effectively eliminated by azole drugs.

Fungicidal and antibiofilm activities of gold nanoparticles on Candida tropicalis.

Aim: To investigate the antifungal activity of two different functionalized gold nanoparticles (AuNP), those stabilized with cetyltrimethylammonium bromide and those conjugated with cysteine, and their effects on the architecture of Candida tropicalis biofilms. Materials & methods: Biofilms were studied by crystal violet binding assay and scanning electron microscopy. We investigated the effects of AuNPs on reactive oxygen species, reactive nitrogen intermediates and enzymatic and nonenzymatic antioxidant defenses. Results/Conclusion: The fungicidal activity and cellular stress of both AuNPs affected biofilm growth through accumulation of reactive oxygen species and reactive nitrogen intermediates. However, cetyltrimethylammonium bromide-stabilized AuNPs revealed a higher redox imbalance. We correlated, for the first time, AuNP effects with the redox imbalance and alterations in the architecture of C. tropicalis biofilms.

Biofilms are at least 100­1000-times more resistant to the effects of antimicrobial agents compared with planktonic cells, and nanoparticles have emerged to provide new approaches to improve the safety and efficacy of antimicrobial therapy. The aim of this work was to investigate the antifungal activity with two different functionalized gold nanoparticles. A significant reduction of Candida tropicalis biofilms with alterations in surface topography and architecture was observed, and the oxidative and nitrosative stress affected the biofilms. To the best of our knowledge, this is the first study that attempts to correlate the antibiofilm effects of gold nanoparticles on the redox imbalance against biofilms. These compounds could be an alternative to fungal biofilms infections treatments, applied specifically in biological and medical fields.

Candida tropicalis induces NLRP3 inflammasome activation via glycogen metabolism-dependent glycolysis and JAK-STAT1 signaling pathway in myeloid-derived suppressor cells to promote colorectal carcinogenesis.

Our previous studies showed that Candida tropicalis promoted colorectal cancer (CRC) by activating the function of MDSCs. However, underlying molecular mechanisms remains to be further investigated. In the present study, we indicated that C. tropicalis induced NLRP3 inflammasome activation through Dectin-3 in myeloid-derived suppressor cells (MDSCs). Mechanistically, we identified that C. tropicalis significantly enhanced the levels of glycolysis dependent on glycogen metabolism in MDSCs, which was required for NLRP3 inflammasome activation. C. tropicalis-induced NLRP3 inflammasome activation of MDSCs required the first priming signal and the second activation signal. For one thing, C. tropicalis promoted transcription of Nlrp3, Pro-caspase-1 and IL-1ß genes through activation of JAK-STAT1 signaling pathway. For another, mtROS as the second activation signal mediated C. tropicalis-induced activation of NLRP3 inflammasome. Pharmacological inhibition of NLRP3 inflammasome activation abolished the pro-tumorigenic effect of C. tropicalis in an AOM/DSS-induced CAC mice model and significantly reduced C. tropicalis-promoted infiltration of MDSCs in colon tumors. Finally, in human CRC samples, the expression of STAT1, p-STAT1 and NLRP3 was elevated in MDSCs infiltrated by CRC. Collectively, these findings shed light on a previously unidentified mechanism by which C. tropicalis induces NLRP3 inflammasome activation in MDSCs to contribute to the progression of CRC. And STAT1-NLRP3 axis might represent a prospective therapeutic target for the treatment of CRC.