Candida auris is an emerging yeast pathogen of global significance. Its multidrug-resistant nature and inadequacies of conventional identification systems pose diagnostic and therapeutic challenges. This study investigated occurrence of C. auris in clinical specimens in Kuwait and its susceptibility to antifungal agents. Clinical yeast strains isolated during 3.5-year period and forming pink-colored colonies on CHROMagar Candida were studied by wet mount examination for microscopic morphology and Vitek 2 yeast identification system. A simple species-specific PCR assay was developed for molecular identification and results were confirmed by PCR-sequencing of rDNA. Antifungal susceptibility testing of one isolate from each patient was determined by Etest. The 280 isolates forming pink-colored colonies on CHROMagar Candida, were identified by Vitek 2 as Candida haemulonii (n = 166), Candida utilis (n = 49), Candida kefyr (n = 45), Candida guilliermondii (n = 9), Candida famata (n = 6) and Candida conglobata (n = 5). Species-specific PCR and PCR-sequencing of rDNA identified 166 C. haemulonii isolates as C. auris (n = 158), C. haemulonii (n = 6) and Candida duobushaemulonii (n = 2). C. auris isolates originated from diverse clinical specimens from 56 patients. Of 56 C. auris isolates tested, all were resistant to fluconazole, 41/56 (73%) and 13/56 (23%) were additionally resistant to voriconazole and amphotericin B, respectively. Eleven (20%) isolates were resistant to fluconazole, voriconazole and amphotericin B. One isolate was resistant to caspofungin and micafungin. Increasing isolation of C. auris in recent years from diverse clinical specimens including bloodstream shows that C. auris is an emerging non-albicans Candida species in Kuwait causing a variety of infections. Inability of conventional identification methods to accurately identify this pathogen and multidrug-resistant nature of many strains calls for a greater understanding of its epidemiology, risk factors for acquiring C. auris infection and management strategies in high-risk patients. This is the first comprehensive study on the emergence of this multidrug-resistant yeast from Kuwait and the Middle East.

Candida glabrata is intrinsically less susceptible to azoles and resistance to echinocandins and reduced susceptibility to amphotericin B has also been detected. Molecular mechanisms of reduced susceptibility (RS) to amphotericin B (AMB) were investigated in C. glabrata strains in Kuwait by sequence analyses of genes involved in ergosterol biosynthesis. A total of 1646 C. glabrata isolates were tested by Etest and results for 12 selected isolates were confirmed by reference broth microdilution. PCR-sequencing of three (ERG2, ERG6 and ERG11) genes was performed for all RS-AMB and 5 selected wild-type C. glabrata isolates by using gene-specific primers. Total cell sterol content was analyzed by gas chromatography-mass spectrometry. Phylogenetic relationship among the isolates was investigated by multilocus sequence typing. Wild-type isolates contained only synonymous mutations in ERG2, ERG6 or ERG11 and total sterol content was similar to reference strains. A nonsynonymous (AGA48AAA, R48K) ERG6 mutation was found in both RS-AMB and wild-type isolates. Four RS-AMB isolates contained novel nonsense mutations at Trp286/Tyr192/Leu341 and 2 isolates contained nonsynonymous (V126F or C198F) mutation in ERG6 and their sterol content were consistent with ERG6 deficiency. Two other RS-AMB isolates contained a novel nonsynonymous (G119S or G122S) ERG2 mutation and their sterol content were consistent with ERG2 deficiency. Of 8 RS-AMB isolates, 1 fluconazole-resistant isolate also contained nonsynonymous Y141H+L381M mutations while 7 isolates contained only synonymous mutations in ERG11. All isolates with ERG6/ERG2/ERG11 mutations were genotypically distinct strains. Our data show that ERG6 and ERG2 are major targets conferring RS-AMB in clinical C. glabrata isolates.

A nine-year prospective study (2002–2010) on the prevalence of Candida dubliniensis among Candida bloodstream isolates is presented. The germ tube positive isolates were provisionally identified as C. dubliniensis by presence of fringed and rough colonies on sunflower seed agar. Subsequently, their identity was confirmed by Vitek2 Yeast identification system and/or by amplification and sequencing of the ITS region of rDNA. In all, 368 isolates were identified as C. dubliniensis; 67.1% came from respiratory specimens, 11.7% from oral swabs, 9.2% from urine, 3.8% from blood, 2.7% from vaginal swabs and 5.4% from other sources. All C. dubliniensis isolates tested by Etest were susceptible to voriconazole and amphotericin B. Resistance to fluconazole (≥8 µg/ml) was observed in 2.5% of C. dubliniensis isolates, 7 of which occurred between 2008–2010. Of note was the diagnosis of C. dubliniensis candidemia in 14 patients, 11 of them occurring between 2008–2010. None of the bloodstream isolate was resistant to fluconazole, while a solitary isolate showed increased MIC to 5-flucytosine (>32 µg/ml) and belonged to genotype 4. A review of literature since 1999 revealed 28 additional cases of C. dubliniensis candidemia, and 167 isolates identified from blood cultures since 1982. In conclusion, this study highlights a greater role of C. dubliniensis in bloodstream infections than hitherto recognized.