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

Abstract

Multilocus sequence typing (MLST) has been successfully applied to the epidemiology of Candida albicansisolates not only within the hospital setting but also in multiple locations nationwide. We performed MLST to investigate the genetic relatedness among bloodstream infection (BSI) isolates of C. albicans recovered from 10 Korean hospitals over a 12-month period. The 156 isolates yielded 112 unique diploid sequence types (DSTs). While 95 DSTs were each derived from a single isolate, 17 DSTs were shared by 61 isolates (39.1%). Interestingly, 111 (71.1%) isolates clustered within previously known clades, and 29 (18.6%) clustered within a new clade that includes strains of Asian origin previously typed as singletons. This MLST study was complemented by restriction endonuclease analysis of genomic DNA using BssHII (REAG-B) in order to evaluate whether strains with identical DSTs and originating from the same hospital corresponded to nosocomial clusters. Importantly, only those isolates with a strong epidemiological relationship showed >95% identical REAG-B types. Our results indicate that REAG-B typing can be complementary to MLST but should be limited to the investigation of isolates of identical DSTs and when interhuman transmission is suspected.

Genetic and phenotypic characterization of Candida albicans strains isolated from infectious disease patients in Shanghai

“…Phylogenetic analysis of our 104 isolates, together with 1485 known DSTs, revealed that 94.2 % of them clustered within 14 of 18 known clades, (clades 1, 3, 4, 6, 7, 8, 9, 11, 12, 14, 15, 16, 17 and 18) and 5.8 % did not cluster within known clades (Fig. 1) (Gong et al, 2012;Odds et al, 2007;Shin et al, 2011). Shin et al (2011) first reported clade 18 as a novel group predominantly consisting of Asian isolates.…”

“…1) (Gong et al, 2012;Odds et al, 2007;Shin et al, 2011). Shin et al (2011) first reported clade 18 as a novel group predominantly consisting of Asian isolates. Indeed, Gong (2012) found that 66.7 % of the strains collected in north China were within clade 18.…”

“…mlst.net/eburst/). According to a method by Shin et al (2011) defining the p-distance between 0.04 and 0.035 that should separate clades, the p-distance threshold of 0.038 was used to define clades.…”

“…In order to assign the Chinese isolates to the existing clades, we performed an analysis of these isolates together with 1485 DSTs retrieved from the MLST database from well-defined clades (61.5 % of all DSTs currently available in the MLST database) (Fig. 1) (Odds et al, 2007;Shin et al, 2011). Of 104 Chinese isolates, 98 (94.2 %) clustered within 14 of the 18 known clades (including Table 1.…”

Multilocus sequence typing of Candida albicans isolates from a burn intensive care unit in Iran

“…MLST is a powerful and useful technique for understanding the epidemiological and evolutionary relationships of pathogenic micro-organisms (Taylor & Fisher, 2003;Urwin & Maiden, 2003;Maiden, 2006;Cliff et al, 2008;Odds & Jacobsen, 2008;Da Matta et al, 2010;Shin et al, 2011). Prevalence of C. albicans infections in the BICU of the Zare hospital (Sari, Iran) led us to investigate the epidemiological relationship of 30 isolates involved using the MLST method.…”