Prevalence of Candida dubliniensis fungemia in Argentina: identification by a novel multiplex PCR and comparison of different phenotypic methods

Abstract

Candida dubliniensis is an emerging pathogen that can cause invasive disease in patients who have a variety of clinical conditions. C. dubliniensis is often misidentified as Candida albicans by clinical laboratories. In Argentina, incidence data are still scarce, and only one systemic infection has been reported. This study aims to determine the prevalence of C. dubliniensis in blood samples in Argentina, to evaluate a novel PCR multiplex as well as several phenotypic methods for the identification of this yeast, and to know the susceptibility profile of isolates against seven antifungal drugs. We have found that prevalence in Argentina appears to be lower than that reported in other countries, occurring only in 0.96% of the Candidemia cases recovered in 47 hospitals during a 1-year period. All C. dubliniensis clinical isolates included in this study were genetically identical when comparing ITS genes sequences. This is in agreement with the previous studies suggesting little genetic variation within this species. The novel multiplex PCR proved to be 100% sensitive and specific for the identification of C. dubliniensis. Therefore, we propose its use as a rapid and inexpensive method for laboratories having access to molecular techniques. Although no single phenotypic test has proved to be infallible, both colony morphology on tobacco agar, as well as abundant chlamydospore formation on both tobacco agar and on sunflower seed agar, may be used as a presumptive differentiation method in routine mycology laboratories. It has been suggested that C. dubliniensis may have higher propensity to develop azole antifungal drug resistance than C. albicans. In this study, one of the five clinical isolates of C. dubliniensis was resistant to fluconazole.