Ensayo de formación y cuantificación de biopelículas mixtas de Candida albicans y Staphylococcus aureus / Formation and quantification assay of Candida albicans and Staphylococcus aureus mixed biofilm

En el presente estudio se cuantificó la producción de biopelículas individuales y mixtas de Candida albicans y Staphylococcus aureus para determinar si dichas biopelículas mixtas se favorecen sinérgicamente. Los ensayos se realizaron utilizando placas de microtitulación de poliestireno de 96 pocillos de fondo plano, se determinó la actividad metabólica de las células en la biopelícula por medio de la reducción enzimática de una sal de tetrazolio (XTT) a través de los cambios colorimétricos que fueron medidos a 490nm. Para visualizar las biopelículas de cada microorganismo y su cinética de crecimiento se utilizo microscopia láser confocal. La mayor formación de biopelícula se observó en las biopelículas mixtas, seguida de las de Candida albicans y, por último, la menor producción la obtuvo Staphylococcus aureus, lo cual nos sugiere la presencia de una relación sinérgica entre los microorganismos ensayados(AU)

This study quantifies the production of single and mixed biofilms of Candida albicans and Staphylococcus aureus to determine if such mixed biofilms have synergistic effects. Assays were performed using polystyrene microtitre plates of 96 wells, metabolic activity was measured by the enzymatic reduction of a tetrazolium salt (XTT) and colorimetric changes were measured at 490nm. Confocal scanning laser microscopy was used to visualise the biofilms of each microorganism and its growth kinetics. The highest levels of biofilm formation were observed in mixed biofilms, followed by those of Candida albicans only, with the lowest levels of biofilm formation being detected for Staphylococcus aureus; all together these results suggest a synergistic relationship between the tested microorganisms(AU)

[Formation and quantification assay of Candida albicans and Staphylococcus aureus mixed biofilm]. / Ensayo de formación y cuantificación de biopelículas mixtas de Candida albicans y Staphylococcus aureus.

This study quantifies the production of single and mixed biofilms of Candida albicans and Staphylococcus aureus to determine if such mixed biofilms have synergistic effects. Assays were performed using polystyrene microtitre plates of 96 wells, metabolic activity was measured by the enzymatic reduction of a tetrazolium salt (XTT) and colorimetric changes were measured at 490 nm. Confocal scanning laser microscopy was used to visualise the biofilms of each microorganism and its growth kinetics. The highest levels of biofilm formation were observed in mixed biofilms, followed by those of Candida albicans only, with the lowest levels of biofilm formation being detected for Staphylococcus aureus; all together these results suggest a synergistic relationship between the tested microorganisms.

Comparación entre métodos convencionales, ChromAgar Candida® y el método de la PCR para la identificación de especies de Candida en aislamientos clínicos / Comparison between conventional methods, ChromAgar Candida® and PCR method for the identification of Candida species in clinical isolates

El incremento en las últimas dos décadas en la incidencia de fungemias causadas por especies levaduriformes en pacientes inmunodeprimidos susceptibles y la poca sensibilidad del cultivo de sangre convencional hacen necesario el desarrollo de enfoques alternativos para la detección temprana y la identificación de las especies responsables. El objetivo de este trabajo ha sido comparar la utilidad de la prueba molecular de la reacción en cadena de la polimerasa (PCR) y métodos convencionales para identificar aislamientos clínicos de diferentes especies, incluyendo el sistema ATB ID32C (bioMérièux, Francia), el cultivo cromogénico Chromagar Candida® (Chromagar, Francia) y la morfogénesis en agar harina de maíz. Se estudiaron 79 aislamientos clínicos en los cuales la especie más prevalente usando el sistema ATB ID32C y la PCR fue C. albicans, seguida por C. tropicalis, C. glabrata y C. krusei. Los patrones de PCR obtenidos para la identificación de aislamientos clínicos fueron estables y consistentes en los diferentes ensayos independientes y mostraron una buena reproducibilidad. Se concluye que la PCR con los cebadores específicos para cada especie, que amplifican los genes ITS1 e ITS2 del ARNr o del gen de la topoisomerasa II, demostró ser un método sensible y específico para la identificación de los aislamientos de C. glabrata C. krusei, C. albicans y, con menor especificidad, para C. tropicalis(AU)

The increase in the incidence of yeast species causing fungemia in susceptible immunocompromised patients in the last two decades and the low sensitivity of conventional blood culture has led to the need to develop alternative approaches for the early detection and identification of causative species. The aim of this study was to compare the usefulness of molecular testing by the polymerase chain reaction (PCR) and conventional methods to identify clinical isolates of different species, using the ID32C ATB system (bioMérieux, France), chromogenic culture Chromagar Candida® (CHROMagar, France) and morphogenesis in corn meal agar. We studied 79 isolates, in which the most prevalent species using the system ID32C and PCR was C. albicans, followed by C. tropicalis, C. glabrata and C .krusei. PCR patterns obtained for the identification of clinical isolates were stable and consistent in the various independent studies and showed good reproducibility, concluding that PCR with species-specific primers that amplify genes ITS1 and ITS2 for rRNA or topoisomerase II primers is a very specific and sensitive method for the identification of C. glabrata, C. krusei, C. albicans, and with less specificity for C. tropicalis(AU)

[Comparison between conventional methods, ChromAgar Candida® and PCR method for the identification of Candida species in clinical isolates]. / Comparación entre métodos convencionales, ChromAgar Candida(®) y el método de la PCR para la identificación de especies de Candida en aislamientos clínicos.

The increase in the incidence of yeast species causing fungemia in susceptible immunocompromised patients in the last two decades and the low sensitivity of conventional blood culture has led to the need to develop alternative approaches for the early detection and identification of causative species. The aim of this study was to compare the usefulness of molecular testing by the polymerase chain reaction (PCR) and conventional methods to identify clinical isolates of different species, using the ID32C ATB system (bioMérieux, France), chromogenic culture Chromagar Candida® (CHROMagar, France) and morphogenesis in corn meal agar. We studied 79 isolates, in which the most prevalent species using the system ID32C and PCR was C. albicans, followed by C. tropicalis, C. glabrata and C .krusei. PCR patterns obtained for the identification of clinical isolates were stable and consistent in the various independent studies and showed good reproducibility, concluding that PCR with species-specific primers that amplify genes ITS1 and ITS2 for rRNA or topoisomerase II primers is a very specific and sensitive method for the identification of C. glabrata, C. krusei, C. albicans, and with less specificity for C. tropicalis.