[Candidemia in Pediatrics: Species distribution and antifungal susceptibility]. / Candidemias en pediatría: distribución de especies y sensibilidad a los antifúngicos.

Serious infections caused by Candida yeasts are frequent in the hospital population. Due to differences in species distribution and antifungal susceptibility testing depending on the geographic area and the type of patient, it is important to study the epidemiology of each institution. For this purpose, we conducted a retrospective, descriptive study on the occurrence of candidemia in the Children's Hospital "Superiora Sor María Ludovica" of the city of La Plata. In a 6-year period (2010-2015), 177 candidemia episodes were recorded. The predominant species were Candida albicans (45%) and Candida parapsilosis (28%). The hospital wards with the highest number of candidemia episodes were the pediatric, neonatal and cardiovascular intensive care units (58%). No resistance to amphotericin B was observed throughout the period whereas resistance to azoles was limited to 4 strains of less frequent species.

[Evaluation of the VITEK 2 system (AST-YSO1 cards) for antifungal susceptibility testing against different Candida species]. / Evaluación de las tarjetas AST-YSO1 del sistema Vitek 2 para determinar la sensibilidad a antifúngicos de levaduras del género Candida.

The aim of this investigation was to evaluate the results of antifungal susceptibility for various Candida species using the Vitek 2 semi-automated system (AST-YSO1 cards, bioMérieux), and to compare them with those obtained by the CLSI (Clinical and Laboratory Standards Institute) broth microdilution reference method (Document M27-A3,2008). The essential agreement (EA) was > 90%, except for Candida glabrata against voriconazole (VCZ); and for Candida krusei against fluconazole (FCZ). The overall categorical agreement (CA) was > 90% when FCZ was evaluated and 89.5% at 24h and 80.7% at 48 h for VCZ. The average time for obtaining results was 15.5h. Minor errors were 7.8% at 24h and 6.1% at 48 h for FCZ, and 10.5% at 24h and 19.3% at 48 h for VCZ. There was only one very major error for FCZ against Candida parapsilosis and no major errors were observed. For amphotericin B, only three isolates showed MICs ≥ 2 µg/ml. The Vitek 2 system detected the MIC value for various Candida species and showed excellent agreement with the reference method proposed by the CLSI.

Evaluation of two commercial methods for the susceptibility testing of Candida species: Vitek 2® and Sensititre YeastOne®.

BACKGROUND: An increased incidence of fungal infections caused by Candida species, especially Candida glabrata and Candida krusei, which are less susceptible to azoles, has been observed. Standardized susceptibility testing is essential for clinical management and for monitoring the epidemiology of resistance. AIMS: We evaluated the performance of two different susceptibility testing commercial methods, Vitek 2® and Sensititre YeastOne®, and compared them with the standard broth microdilution method (CLSI). METHODS: A total of 80 isolates of several Candida species (Candida albicans, Candida parapsilosis complex, Candida tropicalis, C. glabrata and C. krusei) were selected for this study. RESULTS: We analyzed the categorical agreement (CA) between the methods, stratifying the disagreements. The average CA between the methods was 96.3% for Vitek 2® and 84% for Sensititre YeastOne®. No very major errors were observed. Major errors and minor errors were found for all the isolates tested. With the azoles, both Vitek 2® and Sensititre YeastOne® had good and similar performance levels, except for C. tropicalis and C. krusei (Sensititre YeastOne® showed low CA, 56.2%). With the echinocandins, both methods showed good performance for C. albicans, C. parapsilosis and C. tropicalis. However, we observed important discrepancies for C. krusei with caspofungin: Vitek 2® had 100% CA while Sensititre YeastOne® had only 25%. With amphotericin B, both Vitek 2® and Sensititre YeastOne® had good performance with high CA. CONCLUSIONS: Despite the limited isolates tested, we concluded that both methods have good performance and are reliable for antifungal susceptibility testing. However, caspofungin activity against C. krusei and C. glabrata should be interpreted carefully when using Sensititre YeastOne® because we observed a low CA.

Biofilm formation and antifungal susceptibility of Trichosporon asahii isolates from Mexican patients.

BACKGROUND: Trichosporon asahii is a yeast-like fungus that has recently gained importance as a cause of opportunistic systemic infections. The pathogenicity and virulence factors of T. asahii remain largely unknown. Because of the association between invasive infections and the use of catheters and related devices, the ability of the microorganism to adhere and form biofilms may play an important role in the pathogenicity during a trichosporonosis. AIMS: The aim of this study is to identify an association between biofilm formation by T. asahii isolates and their genotype and/or clinical source. METHODS: The biofilm production of 49 T. asahii strains isolated from Mexican patients was measured using the crystal violet stain method, and a comparison made with different adhesion phase incubation times. Antifungal susceptibility testing was performed using a modified CLSI protocol coupled with the quantification of the viable cells with the XTT reduction method. RESULTS: All the T. asahii isolates assayed were able to produce biofilm in vitro, with an intraspecific variability being observed. Overall, increased biofilm production was found when extending the adhesion phase incubation time from 2 to 4h. No association could be established between the biofilm-producing phenotype and either the genotype or clinical source. Higher antifungal resistance to amphotericin B and fluconazole was linked to increased biofilm production by T. asahii. CONCLUSIONS: All clinical isolates tested were able to produce biofilm. No association could be established between biofilm formation and genotype or clinical source.

Current status of the etiology of candidiasis in Mexico.

This study presents a systematic review of the literature on the etiology of superficial and invasive candidiasis in Mexico reported from 2005 to 2015. The data have shown that Candida albicans is the most prevalent species with an increasing tendency of the non-C. albicans Candida species, as reported in other countries. The use of phenotypical methods in the identification of the yeasts limits the identification at the species level, particularly in species that are part of complexes, this is important because the identification only at the genus level leads to inadequate treatment due to the different susceptibility to the antifungals among species. In addition, this finding reveals the need to implement in clinical laboratories the molecular methods for the correct identification of the species involved, and the antifungal susceptibility tests to prevent the etiological changes associated with a poor therapeutic management.

Una experiencia de siete años en el laboratorio de Micología del Hospital de Pediatría Juan P. Garrahan / A seven-year experience in the Mycology Laboratory of Hospital de Pediatría Juan P. Garrahan

En noviembre del año 2015 nos incorporamos al Laboratorio de Micología del Servicio de Microbiología del Hospital Garrahan. En este breve resumen queremos compartir los avances logrados a través de nuestra experiencia durante siete años de trabajo profesional. Debido a los diagnósticos realizados y su complejidad, consideramos que el Hospital Garrahan, sus pacientes y la comunidad toda necesitan contar con un laboratorio de Micología que responda a sus necesidades. Creemos haber iniciado un camino que esperamos continúe y culmine con la creación de la Unidad de Micología (AU)

In November 2015 we joined the Mycology Laboratory of the Microbiology Service of the Hospital Garrahan. In this brief summary we want to share the advances achieved through our experience during seven years of professional work. Due to the diagnosis made and their complexity, we believe that the Hospital Garrahan, its patients and the entire community, need to have a Mycology laboratory that responds to their requirements. We believe we have started a path that we hope will continue and culminate with the creation of the Mycology Unit (AU)

Candidemias en pediatría: distribución de especies y sensibilidad a los antifúngicos / Candidemia in Pediatrics: Species distribution and antifungal susceptibility

Las infecciones graves causadas por levaduras del género Candida son frecuentes en la población hospitalaria. Debido a las diferencias en la distribución de especies y la sensibilidad a los antifúngicos según el área geográfica y el tipo de paciente, resulta importante estudiar la epidemiología de cada institución. Con este propósito, hemos realizado un estudio retrospectivo y descriptivo sobre las candidemias ocurridas en el Hospital de Ninos «Superiora Sor María Ludovica¼ de la ciudad de La Plata. En un período de 6 años (2010-2015) se registraron 177 episodios de candidemia. Las especies predominantes fueron Candida albicans (45%) y Candida parapsilosis (28%). Las salas de internación con mayor cantidad de episodios fueron las unidades de terapia intensiva de pediatría, la neonatal y la cardiovascular (58%). En los casos donde se realizaron pruebas de sensibilidad a los antifúngicos, no se observó resistencia a la anfotericina B en todo el período y la resistencia a azoles se limitó a 4 aislamientos de especies menos frecuentes.

Serious infections caused by Candida yeasts are frequent in the hospital population. Due to differences in species distribution and antifungal susceptibility testing depending on the geographic area and the type of patient, it is important to study the epidemiology of each institution. For this purpose, we conducted a retrospective, descriptive study on the occurrence of candidemia in the Children's Hospital "Superiora Sor María Ludovica" of the city of La Plata. In a 6-year period (2010-2015), 177 candidemia episodes were recorded. The predominant species were Candida albicans (45%) and Candida parapsilosis (28%). The hospital wards with the highest number of candidemia episodes were the pediatric, neonatal and cardiovascular intensive care units (58%). No resistance to amphotericin B was observed throughout the period whereas resistance to azoles was limited to 4 strains of less frequent species.

Evaluación de las tarjetas AST-YSO1 del sistema Vitek 2 para determinar la sensibilidad a antifúngicos de levaduras del género Candida / Evaluation of the VITEK 2 system (AST-YSO1 cards) for antifungal susceptibility testing against different Candida species

El objetivo de este trabajo fue evaluar los resultados de sensibilidad a los antifúngicos de diversas especies de Candida utilizando el sistema semiautomatizado Vitek 2 (tarjetas AST-YSO1; bioMérieux), y compararlos con los obtenidos por el método de referencia del Clinical and Laboratory Standards Institute (CLSI), la microdilución en caldo (Documento M27-A3, 2008). La concordancia esencial fue > 90 %, excepto en el caso de Candida glabrata frente al voriconazol (VCZ) y de Candida krusei frente al fluconazol (FCZ). La concordancia global por categoría (variación no mayor que 2 diluciones, sin discriminar por especie) fue > 90 % cuando se evaluó el FCZ, y 89,5 % a las 24 h y 80,7 % a las 48 h con el VCZ. El tiempo promedio para obtener los resultados fue de 15,5 h. Los errores menores (sensible o resistente por un método y dosis dependiente por el otro) para FCZ fueron de 7,8 % a las 24 h y 6,1 % a las 48 h; para VCZ, 10,5 % a las 24 h y 19,3 % a las 48 h. Solo se detectó 1 error muy mayor (resistente por el método de referencia y sensible por Vitek 2) con Candida parapsilosis frente a FCZ a las 48 h. No se observaron errores mayores (sensibles por el método de referencia y resistentes por Vitek 2). Con respecto a la anfotericina B, solo 3 cepas presentaron una CIM = 2 ?g/ml. El sistema Vitek 2 detectó correctamente el valor de CIM para diversas especies de Candida y presentó una excelente concordancia con el método de referencia propuesto por el CLSI.

The aim of this investigation was to evaluate the results of antifungal susceptibility for various Candida species using the Vitek 2 semi-automated system (AST-YSO1 cards, bioMérieux), and to compare them with those obtained by the CLSI (Clinical and Laboratory Standards Institute) broth microdilution reference method (Document M27-A3,2008). The essential agreement (EA) was > 90%, except for Candida glabrata against voriconazole (VCZ); and for Candida krusei against fluconazole (FCZ). The overall categorical agreement (CA) was > 90% when FCZ was evaluated and 89.5% at 24 h and 80.7% at 48 h for VCZ. The average time for obtaining results was 15.5 h. Minor errors were 7.8% at 24 h and 6.1% at 48 h for FCZ, and 10.5% at 24 h and 19.3% at 48 h for VCZ. There was only one very major error for FCZ against Candida parapsilosis and no major errors were observed. For amphotericin B, only three isolates showed MICs = 2 ?g/ml. The Vitek 2 system detected the MIC value for various Candida species and showed excellent agreement with the reference method proposed by the CLSI.

Evaluación de tres métodos para la detección de la sensibilidad in vitro de especies de Candida a los antifúngicos / Evaluation of three methods for in vitro detection of antifungal susceptibility of Candida species

Los métodos de referencia E. Def 7.1 y M27-A3, que detectan resistencia in vitro a los antifúngicos, son onerosos y muy laboriosos, por lo que su implementación en los laboratorios hospitalarios es limitada. Existen técnicas comerciales de simple realización, que permitirían obtener resultados comparables a los que se obtienen con los métodos estándares. Los objetivos de esta investigación fueron: a) comparar los resultados de concentración inhibitoria mínima obtenidos según el método de referencia E.Def 7.1 con los obtenidos mediante el empleo del equipo comercial ATB® Fungus 3 en un conjunto de 82 aislamientos clínicos de Candida spp. frente a los siguientes antifúngicos: anfotericina B, 5-fluorocitosina, fluconazol e itraconazol; b) comparar en ese mismo conjunto de aislamientos los resultados del estudio de sensibilidad al fluconazol por difusión en agar empleando tabletas Neo-SensitabsTM o discos Malbrán con los que se obtienen por el método de referencia. La concordancia general entre el método de referencia y el ATB® Fungus 3 fue del 90,2 %, mientras que la concordancia del método de referencia con los métodos por difusión con discos y con tabletas alcanzó el 96,3% y el 92,7 %, respectivamente. El ATB® Fungus 3 fue eficaz para determinar la sensibilidad a la anfotericina B y a la 5-fluorocitosina, pero se observaron discrepancias al evaluar la sensibilidad a los azoles. Los métodos por difusión resultaron útiles para determinar la sensibilidad al fluconazol; sin embargo, observamos 3 discrepancias muy mayores, 1 mayor y 2 menores con el método de difusión con tabletas, mientras que con los discos solo se produjeron 3 discrepancias menores.

Reference methods E.Def 7.1 and M27-A3 detect in vitro resistance; however, they are expensive and very laborious. Thus, their actual use in hospital laboratories is limited. There are commercial techniques available, having easier accessibility and development, which would yield results comparable to those of the reference methods. The objectives of this study were: a) to compare the results of minimal inhibitory concentration of 82 Candida spp. clinic isolates according to reference method E.Def 7.1 and ATB® Fungus 3; b) to compare the results of fluconazole susceptibility testing by disk diffusion in agar with Neo-SensitabsTM tablets and Malbrán disks with those of the reference methods. Minimal inhibitory concentration for amphotericin B, 5-flucytosine, fluconazole and itraconazole was performed according to the E.Def 7.1 and the ATB Fungus 3 methods and diffusion was carried out with fluconazole disks and tablets. General concordance between the reference method and ATB Fungus 3 was 90.2 % and 96.3 and 92.7% for diffusion with disks and tablets. The ATB Fungus 3 method was effective to determine susceptibility against amphotericin B and 5-flucytosine; however, discrepancies were observed with azole drugs. Disk diffusion methods are useful to determine susceptibility to fluconazole; however, 3 very major, 1 major and 2 minor errors were observed with the tablets, whereas only 3 minor errors were observed with the disks.