Biofilm formation by oral clinical isolates of Candida species.

We have conducted a longitudinal study to quantify biofilms in oral clinical isolates of Candida species (spp.) from adults with local and systemic predisposing factors for candidiasis. A total of 69 yeast isolates from 63 Mexican patients were evaluated. These isolates (39 C. albicans, 15 C. tropicalis, 7 C. glabrata, 4 C. krusei, 1 C. lusitaniae, 1 C. kefyr, 1 C. guilliermondii and 1 C. pulcherrima) were obtained from two clinical sites: 62.3% (n=43) from the oral mucosa of totally and partially edentulous patients, and 37.7% (n=26) from the oral mucosa of diabetics. In addition, Candida ATCC strains were used as controls for each experiment. The kinetics of biofilm formation were measured by 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide [XTT] reduction; each isolate was tested at 6, 12 and 24h. Biofilm formation is dependent on the Candida spp. and its clinical origin. On average, the oral isolates of C. glabrata are strong biofilm producers, whereas C. albicans and C. tropicalis are moderate producers. The most common species in our population was C. albicans. While the kinetics of C. albicans biofilm formation varies between oral isolates, it generally maintains steady growth from 2 to 48h, when it reaches its maximum growth.

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.