The inhibitory effect of photodynamic therapy on dual-species biofilms of Candida albicans and Candida krusei can be determined by Candida albicans/Candida krusei ratio.

Candida krusei and Candida albicans present the ability to form communities of microorganisms called biofilms. Biofilms can be composed of a single species or more and are an important virulence factor. The inhibition of C. albicans and C. krusei as well as of their dual-species biofilms by antimicrobial Photodynamic Therapy (aPDT) has been demonstrated. This study aimed to investigate the effect of aPDT, with TBO, on dual-species biofilms of C. albicans and C. krusei using different culture mediums, RPMI-1640 and Sabouraud-dextrose broth (SDB) to produce biofilms presenting different C. albicans/C. krusei ratio. Biofilms formed using RPMI-1640 presented a higher C. albicans/C. krusei ratio, however, biofilms formed using SDB presented a predominance of C. krusei. The metabolic activity of biofilms produced using RPMI-1640 was inhibited by aP (∼40%), while biofilms produced using SDB were not affected by aPDT. In addition, biofilm biomass was reduced in biofilms produced using RPMI-1640 and treated with aPDT (∼20%). The results demonstrated that aPDT reduces C. albicans development in dual-species biofilms with C. krusei. However, no effect could be observed on C. krusei, demonstrating that C. krusei, when present in the structure of dual-species biofilms can be resistant to aPDT.

Evaluación del rendimiento del sistema Rapid™ Yeast Pluz (Remel) a partir de 2 medios de cultivo diferentes / Performance evaluation of Rapid™ Yeast Plus (Remel) system from two different culture media

Dentro del género Candida, la especie más frecuentemente aislada de materiales clínicos es Candida albicans. Debido a la emergencia de otras especies que pueden presentar mayor índice de resistencia a los antifúngicos, se hace necesaria la identificación rápida de aquellas. El objetivo del presente trabajo fue evaluar el rendimiento del sistema RapID™ Yeast Plus a partir de subcultivos en 2 formulaciones diferentes, agar Sabouraud dextrosa modificado por Emmons (medio indicado en el inserto del equipo) y agar Sabouraud glucosado, que es el utilizado habitualmente en los laboratorios de la Ciudad Autónoma de Buenos Aires. Se estudiaron 166 cepas de muestras clínicas provenientes de los distintos hospitales que integran la Red de Micología de la Ciudad de Buenos Aires. De los resultados obtenidos se concluye que se deben mantener las condiciones y el medio de cultivo indicado por el fabricante

Within the genus Candida, Candida albicans is the most commonly isolated species from clinical samples. Due to the emergence of other species which can show a higher index of antifungal resistance, a fast identification of these species is necessary. The aim of this work was to evaluate the performance of the RapID Yeast Plus system from two different subculture media formulations: Sabouraud dextrose agar adjusted by Emmons (the medium is indicated in the equipment insert) and Sabouraud glucose agar, which is the most frequently used in Buenos Aires City laboratories. One hundred and sixty-six clinical sample strains coming from different hospitals belonging to the Mycology Network of Buenos Aires City were studied. From the obtained results, we conclude that the conditions and culture medium indicated by the manufacturer should be followed

[Performance evaluation of Rapid™ Yeast Plus (Remel) system from two different culture media]. / Evaluación del rendimiento del sistema Rapid™ Yeast Plus (Remel) a partir de 2 medios de cultivo diferentes.

Within the genus Candida, Candida albicans is the most commonly isolated species from clinical samples. Due to the emergence of other species which can show a higher index of antifungal resistance, a fast identification of these species is necessary. The aim of this work was to evaluate the performance of the RapID Yeast Plus system from two different subculture media formulations: Sabouraud dextrose agar adjusted by Emmons (the medium is indicated in the equipment insert) and Sabouraud glucose agar, which is the most frequently used in Buenos Aires City laboratories. One hundred and sixty-six clinical sample strains coming from different hospitals belonging to the Mycology Network of Buenos Aires City were studied. From the obtained results, we conclude that the conditions and culture medium indicated by the manufacturer should be followed.

The development of animal infection models and antifungal efficacy assays against clinical isolates of Trichosporon asahii, T. asteroides and T. inkin.

The present study developed Galleria mellonella and murine infection models for the study of Trichosporon infections. The utility of the developed animal models was demonstrated through the assessment of virulence and antifungal efficacy for 7 clinical isolates of Trichosporon asahii, T. asteroides and T. inkin. The susceptibility of the Trichosporon isolates to several common antifungal drugs was tested in vitro using the broth microdilution and the E-test methods. The E-test method depicted a lower minimal inhibitory concentration (MIC) for amphotericin and a slightly higher MIC for caspofungin, while MICs observed for the azoles were different but comparable between both methods. All three Trichosporon species established infection in both the G. mellonella and immunosuppressed murine models. Species and strain dependent differences were observed in both the G. mellonella and murine models. T. asahii was demonstrated to be more virulent than the other 2 species in both animal hosts. Significant differences in virulence were observed between strains for T. asteroides in the murine model. In both animal models, fluconazole and voriconazole were able to improve the survival of the animals compared to the untreated control groups infected with any of the 3 Trichosporon species. In G. mellonella, amphotericin was not able to reduce mortality in any of the 3 species. In contrast, amphotericin was able to reduce murine mortality in the T. asahii or T. inkin models, respectively. Hence, the developed animal infection models can be directly applicable to the future deeper investigation of the molecular determinants of Trichosporon virulence and antifungal resistance.