Candida dubliniensis, a new fungal pathogen.
There is a high interest in Candida species other than Candida albicans because of the rise and the epidemiological shifts in candidiasis. These emerging Candida species are favored by the increase of immunocompromised patients and the use of new medical practices, and m. Most oropharyngeal candidiasis can be foundare observed in those HIV-infected patients infected with human immunodeficiency virus (HIV). Candida dubliniensis is a recently described opportunistic pathogen that is closely related to C. albicans but differs from it with respect to epidemiology, certain virulence characteristics, and the ability to develop fluconazole resistance in vitro. C. dubliniensis has been linked to oral candidiasis in AIDS patients, although it has recently been associated to invasive disease. C. dubliniensis shares diagnostic characteristics with C. albicans, as germ tube- and chlamydospore-production, and it is generally misclassified as C. albicans by standard diagnostic procedures. Several recent studies have attempted to elucidate useful phenotypic and genotypic characteristics for separating both species. A large variety of methods have been developed with the aim of facilitating rapid and, accurate identification of this species. These have included differential chromogenic isolation platesculture media, direct immunological tests, and enhanced manual and automated biochemical and enzymatic panels. Chromogenic isolation media, as CHROMagar Candida, demonstrate better detection rates than traditional media, and allow the presumptive identification of C. dubliniensis by means of colony color (dark-green colonies). API 20 C AUX system is considered a reference method, but ID 32 C strip, the VITEK Yeast Biochemical Card and the VITEK 2 ID-YST system correctly identify most C. dubliniensis isolates, being the latter the most accurate. Spectroscopic methods, such as Fourier transformed-infrared spectroscopy, offer potential advantages. However, many authors consider that standard methods for differentiation of Candida species are time-consuming, often insensitive and can fail to distinguish C. dubliniensis. To overcome these low sensitivity, poor specificity and intolerable delay,drawbacks, molecular tools have been developed to discriminate C. dubliniensis, and particularly those based on the polymerase chain reaction. But, molecular tools prove difficult and too complex for routine use in the clinical laboratory setting and new developments are necessary. Moreover, an increased resistance to antifungal drugs has been described. Although preliminary studies indicate that most strains of C. dubliniensis are susceptible to antifungal agents, fluconazole-resistant strains have been detected. Furthermore, fluconazole-resistant strains are easily derived in vitro, showing an increased expression of multidrug resistance transporters, as MDR1.
Departamento de Microbiología, Universidad de Granada, Granada, Spain. josegf@ugr.es
J
J
Gutiérrez
P
P
Morales
M A
MA
González
G
G
Quindós
D000935:Antifungal Agents / Q000494:pharmacology; D002175:Candida / Q000145:classification / Q000187:drug effects / Q000472:pathogenicity*; D002177:Candidiasis / Q000453:epidemiology* / Q000382:microbiology*; D006801:Humans; D009894:Opportunistic Infections / Q000453:epidemiology / Q000382:microbiology; D014774:Virulence
D000935:Antifungal Agents