Differentiation of Candida dubliniensis from Candida albicans on rosemary extract agar and oregano extract agar

Abstract

Candida dubliniensis is a recently described pathogenic species which shares many phenotypic features with Candida albicans and therefore, may be misidentified in microbiological laboratories. Because molecular methods can be onerous and unfeasible in routine mycological laboratories with restricted budgets such as those in developing countries, phenotypic techniques have been encouraged in the development of differential media for the presumptive identification of these species. We examined the colony morphology and chlamydospore production of 30 C. dubliniensis isolates and 100 C. albicans isolates on two new proposed media: rosemary (Rosmarinus officinalis) extract agar (REA) and oregano (Origanum vulgare) extract agar (OEA). These substrates are traditionally used as spices and medicinal herbs. In both of these media, all C. dubliniensis isolates (100%) showed rough colonies with peripheral hyphal fringes and abundant chlamydospores after 24 to 48 hr of incubation at 25 degrees C. In contrast, under the same conditions, all isolates of C. albicans (100%) showed smooth colonies without hyphal fringes or chlamydospores. In conclusion, REA and OEA offer a simple, rapid, and inexpensive screening media for the differentiation of C. albicans and C. dubliniensis.

A Novel Selective Medium for Isolation of Candida dubliniensis

“…and they share many morphological and physiological characteristics, such as germ tube positivity, similar biochemical patterns (10,11) and the ability to form chlamydospores in rice extract agar and corn-meal agar (12,13). This close similarity between the two species has led to the misidentification of isolates of C. dubliniensis as C. albicans.PCR -based molecular methods offer the most reliable alternative for the definition (14)and discrimination of C. dubliniensis,but these tests are labor-intensive and may not be readily available in routine clinical microbiology laboratories.…”

DRBC agar: a new tool for Candida dubliniensis identification

“…Both Niger seed agar and DRBC agar showed 100 % sensitivity and specificity in differentiating C. albicans from C. dubliniensis for the analyzed strains. Specific media have been proposed to discriminate C. dubliniensis from C. albicans, such as Niger seed agar (Staib and Morschhäuser 1999), sunflower agar (Al Mosaid et al 2003) and others (Khan et al 2004;Loreto et al 2006Loreto et al , 2008Ells et al 2009) (Table I). Simple and cheap methods for presumptive differentiation of these two species described but it is well established that C. dubliniensis isolates present large phenotypic variability, which hinders the standardization of the identification techniques (Sullivan and Coleman 1998); therefore the search for new and more elaborated methods is advantageous and should be encouraged.…”

Oral yeast colonization in patients with eating disorders: commensal acquisition or due to purgative habits?

“…The phenotypic characteristics of the isolates (e.g. thermotolerance and chromogenic activity) that lead to the suggestion of C. dubliniensis instead of C. albicans are debated in the literature [8][9][10][11][12][13]18,24 . The present study suggests that conventional methods are not sufficient to discriminate C. albicans from C. dubliniensis, and this is an important concern in clinical practice.…”