Low Level of Antifungal Resistance in Iranian Isolates of Candida glabrata Recovered from Blood Samples in a Multicenter Study from 2015 to 2018 and Potential Prognostic Values of Genotyping and Sequencing of PDR1

Abstract

Establishing an effective empirical antifungal therapy requires that national surveillance studies be conducted. Herein, we report the clinical outcome of infections with and the microbiological features of Iranian isolates of Candida glabrata derived from patients suffering from candidemia. C. glabrata isolates were retrospectively collected from four major cities in Iran; identified by a 21-plex PCR, matrix-assisted laser desorption ionization–time of flight mass spectrometry, and large subunit of ribosomal DNA sequencing; and genotyped by amplified fragment length polymorphism (AFLP). Mutations in PDR1, ERG11, and hot spot 1 (HS1) of FKS1 and FKS2 were investigated, and antifungal susceptibility testing (AFST) was performed (by the CLSI M27-A3 and M27-S4 methods). Seventy isolates of C. glabrata were collected from 65 patients with a median age of 58 years. Fluconazole was the most widely used (29.23%) and least effective antifungal agent. The overall crude mortality rate was 35.4%. Only one strain was resistant to fluconazole, and 57.7% and 37.5% of the isolates were non-wild type (non-WT) for susceptibility to caspofungin and voriconazole, respectively. All isolates showed the WT phenotype for amphotericin B, posaconazole, and itraconazole. HS1 of FKS1 and FKS2 did not harbor any mutations, while numerous missense mutations were observed in PDR1 and ERG11. AFLP clustered our isolates into nine genotypes; among them, genotypes 1 and 2 were significantly associated with a higher mortality rate (P = 0.034 and P = 0.022, α < 0.05). Moreover, 83.3% of patients infected with strains harboring a single new mutation in PDR1, T745A, died despite treatment with fluconazole or caspofungin. Overall, Iranian isolates of C. glabrata were susceptible to the major antifungal drugs. Application of genotyping techniques and sequencing of a specific gene (PDR1) might have prognostic implications.

Candida tropicalis is the most prevalent yeast species causing candidemia in Algeria: the urgent need for antifungal stewardship and infection control measures

“…Except for A. melanogenum and C. tropicalis, which showed elevated MIC values/resistance to azoles, all isolates were susceptible or WT to antifungals tested in this study. The lack of antifungal resistance of C. glabrata in this study is similar to that seen in Iranian [11] and Indian studies [31], and in contrast to the relatively high rate of fluconazole and echinocandin resistance in the USA [6]. Surprisingly, 31.5% of the C. tropicalis isolates (n = 6) were resistant to FLZ, and 50% of those isolates were cross-resistant to the three azoles tested, with 66.6% to VRZ and FLZ, and 83.3% to FLZ and ITZ.…”

“…Surprisingly, 44.1% of the patients did not receive any systemic antifungal treatments and among those treated, FLZ was the most commonly used systemic antimycotic. The low price of FLZ and the high cost of echninocandins are among the factors encouraging medical settings of developing and resource-limited countries to use FLZ for the treatment of the vast majority of candidemia cases [5,11]. We found C. tropicalis as the most prevalent Candida species, while C. albicans ranked third, and C. parapsilosis and C. glabrata were the second and fourth causes of candidemia in Algeria.…”

“…Unfortunately, some of the NAC species, such as C. glabrata [6] and Pichia kudriavzveii [7], intrinsically have higher minimum inhibitory concentration (MIC) values toward azoles, and C. glabrata rapidly acquires resistance to echinocandins [6], the frontline antifungal recommended for the treatment of candidemia [8]. Presently, numerous studies in different countries reported the emergence of C. parapsilosis [9] and C. tropicalis [10] blood isolates resistant to fluconazole, the frontline antifungal drug used to treat candidemia in developing countries [5,11]. Most troubling, the emergence of multidrug-resistant strains of C. glabrata [6] and, more recently, C. auris [12] has led to worrisome therapeutic challenges.…”

Low level of antifungal resistance of Candida glabrata blood isolates in Turkey: Fluconazole minimum inhibitory concentration and FKS mutations can predict therapeutic failure

“…However, some molecular typing studies indicate that a possibility of horizontal transfer, suggesting that clonal enrichment of fluconazole‐resistant C glabrata isolates cannot be excluded 27,28 . Furthermore, it has been shown that some C glabrata genotypes are associated with a higher mortality rate, 29,30 reinforcing the importance of strain profiling using genotyping techniques in clinical practice.…”

Anidulafungin Susceptibility Testing of Candida glabrata Isolates from Blood Cultures by the MALDI Biotyper Antibiotic (Antifungal) Susceptibility Test Rapid Assay

“…Final extension was performed for 8 min at 72°C. PCR products were purified and subsequently directly sequenced by the Sanger sequencing method in a total volume of 10 l including 0.5 l of Big dye, 3 l of green buffer, 2 l of PCR products, and 0.5 l of each primer in separate tubes (37). The results were mapped to C. glabrata CBS 138 (http://www .candidagenome.org) as the reference.…”