Multilocus Sequence Typing for Analyses of Clonality of Candida albicans Strains in Taiwan

Abstract

Multilocus sequence typing (MLST) was used to characterize the genetic profiles of 51 Candida albicans isolates collected from 12 hospitals in Taiwan. Among the 51 isolates, 16 were epidemiologically unrelated, 28 were isolates from 11 critically ill, human immunodeficiency virus (HIV)-negative patients, and 7 were long-term serial isolates from 3 HIV-positive patients. Internal regions of seven housekeeping genes were sequenced. A total of 83 polymorphic nucleotide sites were identified. Ten to 20 different genotypes were observed at the different loci, resulting, when combined, in 45 unique genotype combinations or diploid sequence types (DSTs). Thirty (36.1%) of the 83 individual changes were synonymous and 53 (63.9%) were nonsynonymous. Due to the diploid nature of C. albicans, MLST was more discriminatory than the pulsed-field gel electrophoresis-BssHIIrestricted fragment method in discriminating epidemiologically related strains. MLST is able to trace the microevolution over time of C. albicans isolates in the same patient. All but one of the DSTs of our Taiwanese strain collections were novel to the internet C. albicans DST database (http://test1.mlst.net/). The DSTs of C. albicans in Taiwan were analyzed together with those of the reference strains and of the strains from the United Kingdom and United States by unweighted-pair group method using average linkages and minimum spanning tree. Our result showed that the DNA type of each isolate was patient specific and associated with ABC type and decade of isolation but not associated with mating type, anatomical source of isolation, hospital origin, or fluconazole resistance patterns.

Multilocus Sequence Typing of Candida tropicalis Shows the Presence of Different Clonal Clusters and Fluconazole Susceptibility Profiles in Sequential Isolates from Candidemia Patients in São Paulo, Brazil

“…Fragments of the C. tropicalis genes ICL1, MDR1, SAPT2, SAPT4, XYR1, and ZWF1a have already been analyzed (32,33). Previous reports have indicated that MLST can provide additional information on the mechanisms of genetic variability, such as the persistence, replacement, and microevolution of strains in the hosts (30,34,35).…”

Assessment of Candida glabrata Strain Relatedness by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing

“…Previous genotyping studies indicated that unique or multiple strains of C. albicans from longitudinal surveys or different anatomical sites of the same patient persisted in each human host (6,10,33). Genetic typing of C. glabrata could provide information on strain variation, such as replacement, microvariation, microevolution, and maintenance, to track its distribution in the host (6,33).…”

“…Genetic typing of C. glabrata could provide information on strain variation, such as replacement, microvariation, microevolution, and maintenance, to track its distribution in the host (6,33). Four mating type classes were previously described in C. glabrata, namely, classes I, II, III, and IV (39).…”

“…Recently, the use of multilocus sequence typing (MLST) has been proposed to meet the increasing need for global surveillance and comparison of genotypes in a central database via the Internet. MLST of pathogenic fungal species has been developed to study population structures, such as those of Candida albicans (3,4,6), Candida tropicalis (12,42), and Candida krusei (27). A set of six genes encoding housekeeping functions, comprising the fragments FKS, LEU2, NMT1, TRP1, UGP1, and URA3, is recommended for MLST with C. glabrata (http://cglabrata.mlst.net/) (16).…”

Genetic Diversity among Korean Candida albicans Bloodstream Isolates: Assessment by Multilocus Sequence Typing and Restriction Endonuclease Analysis of Genomic DNA by Use of BssHII

“…Pfaller et al demonstrated previously that some C. albicans BSI strains were more highly concentrated in particular geographic locales and that established BSI strains were endemic in some hospitals (15). Because nosocomial BSIs due to C. albicans constitute an important issue, it has proven quite important to achieve a precise understanding of its epidemiology by use of a reliable typing system (2,5,13,18,20). Several molecular typing methods have been used to track endemic or epidemic C. albicans clones (3).…”