Isolation and molecular identification of Candida dubliniensis from non-human immunodeficiency virus-infected patients in Kuwait

Abstract

Candida dubliniensisis an emerging pathogen capable of causing oropharyngeal, vaginal and bloodstream infections. AlthoughC. dubliniensisis similar toCandida albicansin several phenotypic characteristics, it differs from it with respect to epidemiology, certain virulence factors and the ability to develop resistance to fluconazole rapidly. In this study, the first seven isolations ofC. dubliniensisfrom Kuwait are described, all originating from non-human immunodeficiency virus (HIV)-infected patients. The isolates were initially identified by the Vitek 2 yeast identification system, positive germ tube test, production of rough colonies and chlamydospores on Staib agar and by their inability to assimilate xylose, trehalose or methyl α-d-glucoside. The species identity of the isolates was subsequently confirmed by specific amplification of rDNA targeting the internally transcribed spacer 2 (ITS2), restriction endonuclease digestion of the amplified DNA and direct DNA sequencing of the ITS2. Using the E-test method, the MICs ofC. dubliniensistest isolates were in the range 0.125–0.75 μg ml−1for fluconazole, 0.002–0.75 μg ml−1for itraconazole, 0.006–0.125 μg ml−1for ketoconazole, 0.002–0.5 μg ml−1for amphotericin B and 0.002–0.016 μg ml−1for voriconazole. Two of the isolates were resistant to 5-flucytosine (>32 μg ml−1), but none against fluconazole. The study reinforces the current view thatC. dubliniensishas a much wider geographical and epidemiological distribution.