Genotyping of clinical isolates of Candida glabrata from Iran by multilocus sequence typing and determination of population structure and drug resistance profile

Abstract

Candida glabrata is often the second most common causative agent for candidiasis following Candida albicans. Despite the importance of C. glabrata infections, few epidemiological studies have been conducted on this issue. The goal of this study was genotyping of clinical isolates of C. glabrata by multilocus sequence typing (MLST) technique for determination of the endemic prevalent genotypes and any association between isolation source and drug resistance. A total of 50 C. glabrata clinical isolates from Iran were analyzed by MLST and tested for in-vitro susceptibilities to amphotericin-B, caspofungin, fluconazole, and voriconazole according to the Clinical Laboratory Standards Institute (CLSI) M27-A4 document guidelines. Among these isolates, 16 distinct STs were identified, indicating a discriminatory power index of 0.9029. The three major sequence types (STs) were ST-59, ST-74, and ST-7 with 10, 8, and 7 isolates, respectively. Furthermore, a total of 11 new sequences were found, to which no allele numbers were assigned in the MLST database. All the isolates were susceptible to amphotericin B and caspofungin. Fluconazole resistance was shown in four isolates. Also, a sole isolate was voriconazole resistant. This study shows that the population structure of C. glabrata in Iran consists of groups closely related to the global database as well as to some new clonal clusters and STs. Regarding the high prevalence of 11 new sequences found in this study, it can be concluded that, these new alleles are among the endemic genotypes of Iran. The genotypes or STs were independent of drug susceptibility and anatomic sources.

Microsatellite Typing and Antifungal Susceptibility of Candida glabrata Strains Isolated From Patients With Candida Vaginitis

“…Our findings highlighted a positive association of C. glabrata population structures with the predominant genotype (GT27) and r/non-WT to antifungal drugs which is consistent with those of Dhieb et al (2015). In contrast, other researchers have found no correlation between the predominant genotype or genotypes with antifungal resistance (De Meeûs et al, 2002; Dodgson et al, 2003; Abbes et al, 2011; Klotz et al, 2016; Amanloo et al, 2017). This discrepancy may be due to the differences in geographical locations, the treatment protocols used in different areas, self-medication by patients, sociocultural conditions of people, and other effective factors on drug resistance.…”

“…In vitro antifungal susceptibility tests and molecular typing are two major keys in epidemiological studies. Several methods have been used for the identification and typing of Candida species including multilocus sequence typing (MLST), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), multilocus enzyme electrophoresis (MLEE), and fingerprinting with complex DNA probes (Dodgson et al, 2003; Dhieb et al, 2015; Amanloo et al, 2017). However, microsatellite analysis based on short tandem repeats (STR’s) has been considered as a rapid and reliable technique with a highly discriminatory power (DP) for typing of C. glabrata (Abbes et al, 2012;Hou et al, 2017).…”

Whole Genome Sequencing of Australian Candida glabrata Isolates Reveals Genetic Diversity and Novel Sequence Types

“…In particular, the use of a standardized 6-locus MLST system (Dodgson et al, 2003) has improved discrimination between isolates with good reproducibility and portability of data via internet-accessible databases. Major findings from MLST analyses highlight that despite description of a broad range of MLST sequence types (STs), C. glabrata appears to be highly clonal with infrequent emergence of novel STs, which may be restricted to various geographical regions (Lott et al, 2012; Hou et al, 2017; Amanloo et al, 2018). This observed clonality however, may be fluid with temporal shifts of the major C. glabrata subtypes documented over time in one study (Lott et al, 2010).…”

MSH2 Gene Point Mutations Are Not Antifungal Resistance Markers in Candida glabrata

“…Furthermore, MSH2 gene sequences were mostly identical in the isolates belonging to a given ST or microsatellite genotype, with some exceptions (Fig. 1) (19,22).…”