Candidemia in Colombia

Molecular Evaluation of the mRNA Expression of the ERG11, ERG3, CgCDR1, and CgSNQ2 Genes Linked to Fluconazole Resistance in Candida glabrata in a Colombian Population

INTRODUCTION

The study of Candida glabrata genes associated with fluconazole resistance, from a molecular perspective, increases the understanding of the phenomenon with a view to its clinical applicability.

OBJECTIVE

We sought to establish the predictive molecular profile of fluconazole resistance in Candida glabrata by analyzing the ERG11, ERG3, CgCDR1, and CgSNQ2 genes.

METHOD

Expression was quantified using RT-qPCR. Metrics were obtained through molecular docking and Fisher discriminant functions. Additionally, a predictive classification was made against the susceptibility of C. glabrata to fluconazole.

RESULTS

The relative expression of the ERG3, CgCDR1, and CgSNQ2 genes was higher in the fluconazole-resistant strains than in the fluconazole-susceptible, dose-dependent strains. The gene with the highest relative expression in the fluconazole-exposed strains was CgCDR1, and in both the resistant and susceptible, dose-dependent strains exposed to fluconazole, this was also the case. The molecular docking model generated a median number of contacts between fluconazole and ERG11 that was lower than the median number of contacts between fluconazole and ERG3, -CgCDR1, and -CgSNQ2. The predicted classification through the multivariate model for fluconazole susceptibility achieved an accuracy of 73.5%.

CONCLUSION

The resistant strains had significant expression levels of genes encoding efflux pumps and the ERG3 gene. Molecular analysis makes the identification of a low affinity between fluconazole and its pharmacological target possible, which may explain the lower intrinsic susceptibility of the fungus to fluconazole.

Candida Non-albicans and Non-auris Causing Invasive Candidiasis in a Fourth-Level Hospital in Colombia: Epidemiology, Antifungal Susceptibility, and Genetic Diversity

Increasingly common and associated with healthcare settings, Candida infections are very important, since some species of this genus can develop antifungal resistance. We contribute data on the epidemiology, antifungal susceptibility, and genetic diversity of Candida non-albicans and non-auris affecting critically ill patients in a fourth-level hospital in Colombia. Ninety-seven isolates causing invasive infections, identified by conventional methods over 18 months, were studied. Data from patients affected by these yeasts, including sex, age, comorbidities, treatment, and outcome, were analysed. The antifungal susceptibility of the isolates was determined, and the ribosomal DNA was sequenced. Candida parapsilosis, Candida tropicalis, Candida glabrata, Candida dubliniensis, and Candida guilliermondii caused 48.5% of all cases of invasive candidiasis. The species were mainly recovered from blood (50%). Patients were mostly men (53.4%), between 18 days and 93 years old, hospitalized in the ICU (70.7%). Overall mortality was 46.6%, but patients in the ICU, using antibiotics, with diabetes mellitus, or with C. glabrata infections were more likely to die. Resistant isolates were identified in C. parapsilosis, C. tropicalis, and C. glabrata. This study provides epidemiological data for the surveillance of emerging Candida species, highlighting their clinical impact, as well as the emergence of antifungal resistance and clonal dispersal.

Prevalence and Species Distribution of Candida Clinical Isolates in a Tertiary Care Hospital in Ecuador Tested from January 2019 to February 2020

The incidence of candidemia in healthcare centers is associated with high morbidity and mortality. Frequency varies significantly among regions, with some species being more prevalent than others in Latin America. In this study, 191 clinical Candida isolates were collected from a major hospital in Ecuador from January 2019 to February 2020 aiming to assess their prevalence and distribution. After data processing, 168 isolates characterized by the VITEK 2 system were subsequently identified by ITS sequencing. Results showed diverse Candida species distributions, with C. albicans and C. tropicalis being the most prevalent across different clinical sources. In hospitalized individuals, C. tropicalis (38%) and C. albicans (37%) were the most prevalent, followed by, C. parapsilosis (16%), C. glabrata (5%), and other non-Candida albicans (NCA) species (6%). Conversely, C. parapsilosis (48%), C. albicans (20%), and C. glabrata (14%), associated with candidemia, were the most common in blood and CSF. Additionally, uncommon NCA species such as C. haemulonii, C. kefyr, and C. pelliculosa were identified in Ecuador for the first time. Discrepancies in species identification were observed between the VITEK 2 system and ITS sequencing, coinciding at 85%. This highlights the need for ongoing surveillance and identification efforts in Ecuador's clinical and epidemiological settings.

Study of Candidemia and its Antifungal Susceptibility Profile at the University Hospital of Montevideo, Uruguay

Systemic candidiasis are high mortality infections caused by yeasts of the genus Candida, affecting patients with numerous risk factors. Nowadays, candidemia produced by "non-albicans" species has increased considerably. Timely diagnosis and subsequent treatment substantially improve patients' survival. Our objectives are to study the frequency, distribution, and antifungal susceptibility profiles of candidemia isolates in our hospital. We conducted a descriptive, cross-sectional study. Positive blood cultures were recorded from January 2018 to December 2021. Positive Candida genus blood cultures were selected, classified, and analyzed on their susceptibility profile for amphotericin B, fluconazole and caspofungin using AST-YS08® card for VITEK 2 Compact® to determine minimum inhibitory concentration (MIC) and CLSI M60 2020 2nd Edition to determine breakpoints. 3862 positive blood cultures were obtained, 113 (2.93%) presented growth of Candida spp., corresponding to 58 patients. 55.2% came from the Hospitalization Ward and Emergency Services and 44.8% from the Intensive Care Unit. The species were distributed as follows: Nakaseomyces glabratus (Candida glabrata) (32.74%), Candida albicans (27.43%), Candida parapsilosis (23.01%), Candida tropicalis (7.08%) and others (9.73%). Most species were found to be susceptible to most antifungals, except for C. parapsilosis, presenting 4 isolates with resistance to fluconazole and N. glabratus (C. glabrata), whose clinical susceptibility data remains insufficient to provide accurate breakpoints. The percentage of recorded positive blood cultures of Candida spp. was 2.93%, these results were consistent with those reported at a regional level. A predominance of "non-albicans" species was observed. It is essential to know the prevalence, epidemiology, and susceptibility profiles of candidemia in our country, as well as being updated on its subsequent changes, maintaining epidemiological surveillance. This allows professionals to map out early and effective therapeutic strategies, staying alert of possible multi-resistant strains.

Therapeutic Use of the Antimicrobial Peptide PNR20 to Resolve Disseminated Candidiasis in a Murine Model

Invasive fungal infections (IFIs) caused by Candida species are an emerging threat globally, given that patients at-risk and antifungal resistance are increasing. Antimicrobial peptides (AMPs) have shown good therapeutic capacity against different multidrug-resistant (MDR) microorganisms. This study evaluated the activity of the synthetic peptide, PNR20, against Candida albicans ATCC 10231 and a MDR Colombian clinical isolate of Candida auris. Perturbation of yeast cell surface was evaluated using scanning electron microscopy. Cell viability of Vero cells was determined to assess peptide toxicity. Additionally, survival, fungal burden, and histopathology of BALB/c mice infected intravenously with each Candida species and treated with PNR20 were analyzed. Morphological alterations were identified in both species, demonstrating the antifungal effect of PNR20. In vitro, Vero cells' viability was not affected by PNR20. All mice infected with either C. albicans or C. auris and treated with PNR20 survived and had a significant reduction in the fungal burden in the kidney compared to the control group. The histopathological analysis in mice infected and treated with PNR20 showed more preserved tissues, without the presence of yeast, compared to the control groups. This work shows that the utilization of PNR20 is a promising therapeutic alternative against disseminated candidiasis.

Method validation for the quantification of fluconazole and its organic impurities in raw material using high-performance liquid chromatography

Introduction. The real laboratory conditions of each country, including climate, can affect the method’s efficiency in analyzing a pharmacological substance. Thus, it is necessary to validate the process according to the corresponding guidelines and optimize it to ensure success and confidence in the results. Objective. The objective was to validate a methodology for fluconazole and its organic impurities quantification in raw material using high-performance liquid chromatography, with a diode array detector, under tropical climate conditions, and complying with all regulatory requirements. Materials and methods. We performed pre-validation tests of the method consisting of system adequacy, filters study, quantification limit, absence of systematic error, forced degradation studies, and solutions stability. In addition, we validated the specificity, linearity, accuracy, precision, and robustness of the system. Results. Separation of the degradation products from the analyte peaks allowed the achievement of the method’s spectral purity. The solution’s stability was not affected during the evaluated time (24 hours) at room temperature and under refrigeration. Linearity resulted in correlation coefficients greater than or equal to 0.999 for the evaluation and greater than or equal to 0.997 for impurities. We obtained a fluconazole recovery varying from 98 to 102% with an accuracy between 80 to 120% for impurities detection. The repeatability and reproducibility factor did not exceed a relative standard deviation of 2.0% for the evaluation and of 5.0% for the impurities, demonstrating the adequate robustness of the method. In addition, a short analysis execution time allowed the quick determination of the raw material quality. Conclusion. We demonstrated that the fluconazole quantification method validated by high-performance liquid chromatography is sufficiently selective, precise, exact, linear, and robust to generate accurate analytical results under real conditions, including the tropical climate of Colombia.

Lippia origanoides Essential Oil or Thymol in Combination with Fluconazole Produces Damage to Cells and Reverses the Azole-Resistant Phenotype of a Candida tropicalis Strain

Candida tropicalis is one of the most pathogenic species within the genus. Increased antifungal resistance has been reported, which is in part due to the organism's ability to form biofilms. In natural products derived from plants, such as essential oils (EOs) or their major components, there is significant potential to develop new antifungals or to both enhance the efficacy and reduce the toxicity of conventional antifungals. This study aimed to evaluate the effect of combining an EO of Lippia origanoides or thymol with fluconazole on an azole-resistant C. tropicalis strain. Synergism was observed in the combination of fluconazole with the EO and with thymol, and minimal inhibitory concentrations for fluconazole decreased at least 32-fold. As a consequence of the synergistic interactions, mitochondrial membrane potential was reduced, and mitochondrial superoxide production increased. Alteration in nuclear morphology, cell surface, and ultrastructure was also observed. In conclusion, the synergistic interaction between L. origanoides EO or thymol with fluconazole reverted the azole-resistant C. tropicalis phenotype. These findings suggest that L. origanoides EO or thymol alone, or in combination with fluconazole, have the potential for development as antifungal therapies for this yeast, including resistant strains.

Combining the Peptide RWQWRWQWR and an Ethanolic Extract of Bidens pilosa Enhances the Activity against Sensitive and Resistant Candida albicans and C. auris Strains

The antifungal activity of palindromic peptide RWQWRWQWR and its derivatives was evaluated against clinical isolates of Candida albicans and C. auris. Also, Bidens pilosa ethanolic extracts of leaves and stem were evaluated. Furthermore, combinations of peptide, extract, and/or fluconazole (FLC) were evaluated. The cytotoxicity of peptides and extracts in erythrocytes and fibroblasts was determined. The original palindromic peptide, some derivative peptides, and the ethanolic extract of leaves of B. pilosa exhibited the highest activity in some of the strains evaluated. Synergy was obtained between the peptide and the FLC against C. auris 435. The combination of the extract and the original palindromic peptide against C. albicans SC5314, C. auris 435, and C. auris 537 decreased the minimal inhibitory concentrations (MICs) by a factor of between 4 and 16. These mixtures induced changes in cell morphology, such as deformations on the cell surface. The results suggest that the combination of RWQWRWQWR and B. pilosa extract is an alternative for enhancing antifungal activity and decreasing cytotoxicity and costs and should be considered to be a promising strategy for treating diseases caused by Candida spp.

In Vitro Antifungal Activity of Three Synthetic Peptides against Candida auris and Other Candida Species of Medical Importance

Candidiasis is an opportunistic infection affecting immunosuppressed and hospitalized patients, with mortality rates approaching 40% in Colombia. The growing pharmacological resistance of Candida species and the emergence of multidrug-resistant Candida auris are major public health problems. Therefore, different antimicrobial peptides (AMPs) are being investigated as therapeutic alternatives to control candidiasis effectively and safely. This work aimed to evaluate the in vitro antifungal activity of three synthetic AMPs, PNR20, PNR20-1, and 35409, against ATCC reference strains of Candida albicans, Candida glabrata, Candida parapsilosis, Candida krusei, and Candida tropicalis, and clinical isolates of C. auris. Antifungal susceptibility testing, determined by broth microdilution, showed that the AMPs have antifungal activity against planktonic cells of all Candida species evaluated. In C. auris and C. albicans, the peptides had an effect on biofilm formation and cell viability, as determined by the XTT assay and flow cytometry, respectively. Also, morphological alterations in the membrane and at the intracellular level of these species were induced by the peptides, as observed by transmission electron microscopy. In vitro, the AMPs had no cytotoxicity against L929 murine fibroblasts. Our results showed that the evaluated AMPs are potential therapeutic alternatives against the most important Candida species in Colombia and the world.

Mortality Caused by Candida auris Bloodstream Infections in Comparison with Other Candida Species, a Multicentre Retrospective Cohort

Candida auris is an emerging pathogen considered to be critical in the World Health Organization fungal organisms list. The study aims to determine the mortality and hospital stays attributed to Candida auris (C. auris) compared to other Candida species in adult patients with candidemia. A retrospective cohort of adults with candidemia was examined from seven centres in Colombia between 2016 and 2021. The primary outcome was 30-day mortality, and the secondary outcome was the length of hospital stay among survivors. Adjustment of the confounding variables was performed using inverse probability weights of exposure propensity score (candidemia by C. auris), survival regression models (Weibull distribution), and a counting model (negative binomial distribution). A value of 244 (47.6%) of the 512 patients with candidemia died within the first 30 days. The crude mortality in C. auris was 38.1% vs. 51.1% in Candida non-auris (CNA). In the Weibull model, mortality in the C. auris group was lower (adjusted HR: aHR- 0.69, 95% CI: 0.53-0.90). Antifungal treatment also decreased mortality, with an aHR of 0.36 (95% CI 0.27-0.47), while the presence of septic shock on patient progression increased it, with an aHR of 1.73 (95% CI 1.41-2.13). Among the patients who survived, no differences in the length of hospital stay were observed between the C. auris and the CNA groups, with an incidence rate ratio of 0.92 (95% CI: 0.68-1.22). Mortality in patients with C. auris bloodstream infections appears lower when adjusted for numerous confounding variables regarding treatment and the presence of septic shock in patient progression. We identified no significant effect of C. auris on the length of hospital stay in surviving patients.

Isoespintanol Antifungal Activity Involves Mitochondrial Dysfunction, Inhibition of Biofilm Formation, and Damage to Cell Wall Integrity in Candida tropicalis

The growing increase in infections caused by C. tropicalis, associated with its drug resistance and consequent high mortality, especially in immunosuppressed people, today generates a serious global public health problem. In the search for new potential drug candidates that can be used as treatments or adjuvants in the control of infections by these pathogenic yeasts, the objective of this research was to evaluate the action of isoespintanol (ISO) against the formation of fungal biofilms, the mitochondrial membrane potential (ΔΨm), and its effect on the integrity of the cell wall. We report the ability of ISO to inhibit the formation of biofilms by up to 89.35%, in all cases higher than the values expressed by amphotericin B (AFB). Flow cytometric experiments using rhodamine 123 (Rh123) showed the ability of ISO to cause mitochondrial dysfunction in these cells. Likewise, experiments using calcofluor white (CFW) and analyzed by flow cytometry showed the ability of ISO to affect the integrity of the cell wall by stimulating chitin synthesis; these changes in the integrity of the wall were also observed through transmission electron microscopy (TEM). These mechanisms are involved in the antifungal action of this monoterpene.

Antifungal Activity of Mycogenic Silver Nanoparticles on Clinical Yeasts and Phytopathogens

In this study, seven different silver nanoparticles (AgNPs) were obtained using the fungi species from the phylum Ascomycota, Aspergillus tubingensis, Aspergillus spp., Cladosporium pini-ponderosae, Fusarium proliferatum, Epicoccum nigrum, Exserohilum rostratum, and Bionectria ochroleuca, isolated from the Brazilian biodiversity, particularly from the mangrove and Caatinga biomes. The nanoparticles were coded as AgNP-AT, AgNP-Asp, AgNP-CPP, AgNP-FP, AgNP-EN, AgNP-ER, and AgNP-BO and characterized using spectrophotometry (UV-Vis), dynamic light scattering (DLS), zeta potential, transmission electron microcopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. All the AgNPs presented homogeneous size in the range from 43.4 to 120.6 nm (DLS) and from 21.8 to 35.8 nm (TEM), pH from 4.5 to 7.5, negative charge, and presence of protein coating on their surface. The antifungal activity of the AgNPs was evaluated on clinical strains of Candida albicans, and on the non-albicans species, Candida krusei, Candida glabrata, Candida parapsilosis, Candida tropicalis, and Candida guilliermondii, common in hospital infections, and against the phytopathogens Fusarium oxysporum, Fusarium phaseoli, Fusarium sacchari, Fusarium subglutinans, Fusarium verticillioides, and Curvularia lunata, which are species responsible for serious damage to agriculture production. The AgNPs were effective against the yeasts with MICs ranging from 1.25 to 40 µM and on the phytopathogens with MICs from 4 to 250 µM, indicating the promising possibility of application of these AgNPs as antifungal agents. The results indicated that the physicochemical parameters of the AgNPs, including the functional groups present on their surface, interfered with their antifungal activity. Overall, the results indicate that there is no specificity of the AgNPs for the yeasts or for the phytopathogens, which can be an advantage, increasing the possibility of application in different areas.

Mechanism of Antifungal Action of Monoterpene Isoespintanol against Clinical Isolates of Candida tropicalis

The growing increase in infections by Candida spp., non-albicans, coupled with expressed drug resistance and high mortality, especially in immunocompromised patients, have made candidemia a great challenge. The efficacy of compounds of plant origin with antifungal potential has recently been reported as an alternative to be used. Our objective was to evaluate the mechanism of the antifungal action of isoespintanol (ISO) against clinical isolates of Candida tropicalis. Microdilution assays revealed fungal growth inhibition, showing minimum inhibitory concentration (MIC) values between 326.6 and 500 µg/mL. The eradication of mature biofilms by ISO was between 20.3 and 25.8% after 1 h of exposure, being in all cases higher than the effect caused by amphotericin B (AFB), with values between 7.2 and 12.4%. Flow cytometry showed changes in the permeability of the plasma membrane, causing loss of intracellular material and osmotic balance; transmission electron microscopy (TEM) confirmed the damage to the integrity of the plasma membrane. Furthermore, ISO induced the production of intracellular reactive oxygen species (iROS). This indicates that the antifungal action of ISO is associated with damage to membrane integrity and the induction of iROS production, causing cell death.

Invasive Candidiasis: Update and Current Challenges in the Management of This Mycosis in South America

Invasive candidiasis encompassing Candida bloodstream infections and deep-seated candidiasis can become a persistent health problem. These infections are caused by Candida species and have high morbidity and mortality rates. Species distribution, access to diagnosis, treatment and mortality are different around the world. The mortality rate is high in South America (30–70%), and Candida albicans is the most prevalent species in this region. However, a global epidemiological shift to non-albicans species has been observed. In this group, C. parapsilosis is the species most frequently detected, followed by C. tropicalis, and at a slower rate, C. glabrata, which has also increased, in addition to the emerging C. auris, resistance to several drugs. This article summarizes relevant aspects of candidemia pathogenesis, such as the mechanisms of fungal invasion, immune response, and the impact of genetic defects that increase host susceptibility to developing the infection. We also discuss relevant aspects of treatment and future challenges in South America.

Pathogenicity Assessment of Colombian Strains of Candida auris in the Galleria mellonella Invertebrate Model

Candida auris, first described in 2009, is an opportunistic pathogenic yeast that causes nosocomial outbreaks around the world, with high mortality rates associated with therapeutic failure. In this study, we evaluated the pathogenicity of 107 isolates from two cities in Colombia, associated with fungemia or colonization processes; to achieve this, we used the Galleria mellonella invertebrate model to compare pathogenicity. Our results showed that less than half of the total isolates of C. auris presented a high pathogenicity compared to the reference strain SC5314, and most of those highly pathogenic strains were from colonization processes. We observed that there was formation of large aggregates of cells that cannot be disrupted easily, without statistically significant differences between the pathogenicity of the aggregated and non-aggregated strains. In addition, protease activity was observed in 100% of the C. auris strains; phospholipase and hemolysin activity were observed in 67.3 and 68.2% of the studied strains, respectively. In conclusion, these results highlight the utility of determining survival using G. mellonella, which allowed us to provide new information on the pathogenicity, enzymatic activity, and the relationship of the aggregated and non-aggregated phenotypes of C. auris in this model.

Infección invasiva por Candida spp. En pacientes inmunocomprometidos: Descripción de curso clínico experiencia diagnóstica, manejo y seguimiento en centro de alta complejidad

Introducción: Candida spp. Es la principal causa de fungemia, cuya incidencia ha aumentado en los últimos años. Existen datos locales insuficientes sobre este tipo de infecciones. Materiales y métodos: Este fue un estudio observacional retrospectivo de 44 pacientes diagnosticados con candidiasis invasiva hospitalizados en la Fundación Valle del Lili, el cual es un centro de cuarto nivel afiliado a la Universidad Icesi en el Suroccidente Colombiano, entre los años 2012 a 2017. Resultados: Se identificaron 44 pacientes con candidiasis invasiva, 27 de ellos mujeres (61%). La mediana de edad fue de 56 años (36 – 70). Más del 50% tenían una enfermedad crónica subyacente, uso de antibióticos (84%), catéter venoso central (80%), ventilación mecánica (68%) y nutrición enteral (66%) El 80% requirió manejo en unidad de cuidados intensivos (UCI) donde debutaron con sepsis (68%) y falla respiratoria (61%). En el 90% de los casos se aisló alguna especie de Candida spp. A partir de hemocultivo y sólo al 22% se le realizó prueba de sensibilidad. El tratamiento de elección fue con fluconazol (80%), asociado a caspofungina (70%). La tasa de mortalidad fue del 49%, con una mediana de 33 (22-49,5) días desde el ingreso hasta el fallecimiento. C. albicans fue el principal microorganismo aislado. La resistencia a azoles en especies no albicans existe en nuestro medio. Conclusión: La candidiasis se presenta como candidemia asociada a infección bacteriana concomitante, que cobra mayor importancia en el contexto del paciente inmunosuprimido asociado a elevadas tasas de mortalidad.