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

Abstract

Candida dubliniensis is an emerging pathogen capable of causing oropharyngeal, vaginal and bloodstream infections. Although C. dubliniensis is similar to Candida albicans in 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 of C. dubliniensis from 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 AE-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 of C. dubliniensis test isolates were in the range 0 . 125-0 . 75 ìg ml À1 for fluconazole, 0 . 002-0 . 75 ìg ml À1 for itraconazole, 0 . 006-0 . 125 ìg ml À1 for ketoconazole, 0 . 002-0 . 5 ìg ml À1 for amphotericin B and 0 . 002-0 . 016 ìg ml À1for voriconazole. Two of the isolates were resistant to 5-flucytosine (.32 ìg ml À1 ), but none against fluconazole. The study reinforces the current view that C. dubliniensis has a much wider geographical and epidemiological distribution.

Trichosporon asahii causing nosocomial urinary tract infections in intensive care unit patients: genotypes, virulence factors and antifungal susceptibility testing

“…horizontal shaking for 24-48 h at 35 uC. T. asahii strains were first identified via VITEK-2 Compact with YST cards, and then verified through DNA sequencing of the internal transcribed spacer (ITS) locus of the rDNA, using primers ITS1/ITS4 (ITS1 : 59-TCCGTAGGTGAACCTGCGG-39; ITS4 : 59-TCCTCCGC-TTATTGATATGC-39) (Ahmad et al, 2004).…”

Novel 5-Flucytosine-Resistant Clade of Candida dubliniensis from Saudi Arabia and Egypt Identified by Cd25 Fingerprinting

“…However, two recent studies reported that 18/32 (56%) and 2/7 (29%) C. dubliniensis isolates tested from Saudi Arabia (17) and Kuwait (1), respectively, were 5FC resistant (MIC Ͼ 32 g/ml). On the basis of the results of the present study, it is interesting to speculate that the 5FC-resistant C. dubliniensis isolates described by Fotedar and Al Hedaithy (17) and Ahmad et al (1) may also belong to the CD25 group III clade. In support of this suggestion, a recent study demonstrated that 5FC resistance in C. albicans is restricted to a single genetic clade (38).…”

“…There have been several reports describing the recovery of C. dubliniensis isolates in a variety of Middle Eastern countries (1,17,18,26), but little is known about the population structure or the epidemiology of these isolates or their relationship to isolates recovered in the rest of the world. Gee et al (18) included eight independent isolates of C. dubliniensis recovered in Israel in their study, four of which belonged to Cd25 group I (genotype 1), with the other four belonging to Cd25 group II.…”

“…Several previous studies have reported that the majority of C. dubliniensis clinical isolates reported in the literature are susceptible to commonly used antifungal drugs, including azoles, amphotericin B, and 5FC (29,30,32,33,39). However, two recent studies reported an unusually high prevalence of 5FC resistance among C. dubliniensis isolates from Saudi Arabia and Kuwait (1,17). In order to investigate whether there is an association between the Cd25 group III isolates identified in the present study and resistance to 5FC, all of the Saudi Arabian, Egyptian, and Israeli C. dubliniensis isolates included in the study were tested for susceptibility to 5FC with the NCCLSapproved broth microdilution method (31).…”

A Ser29Leu Substitution in the Cytosine Deaminase Fca1p Is Responsible for Clade-Specific Flucytosine Resistance in Candida dubliniensis

“…In C. dubliniensis, the resistance patterns are more clearly defined, with 5FC-susceptible isolates exhibiting 5FC MICs of Յ0.125 g/ml and 5FC-resistant isolates exhibiting 5FC MICs of Ն128 g/ml (4). To date, 5FC resistance in C. dubliniensis has been reported only in isolates from the Middle East, all of which that have been tested belong to MLST clade C3 (1,4,18,29).…”