Multilocus Sequence Typing of Pathogenic Candida albicans Isolates Collected from a Teaching Hospital in Shanghai, China: A Molecular Epidemiology Study

Abstract

Molecular typing of Candida albicans is important for studying the population structure and epidemiology of this opportunistic yeast, such as population dynamics, nosocomial infections, multiple infections and microevolution. The genetic diversity of C. albicans has been rarely studied in China. In the present study, multilocus sequence typing (MLST) was used to characterize the genetic diversity and population structure of 62 C. albicans isolates collected from 40 patients from Huashan Hospital in Shanghai, China. A total of 50 diploid sequence types (DSTs) were identified in the 62 C. albicans isolates, with 41 newly identified DSTs. Based on cluster analysis, the 62 isolates were classified into nine existing clades and two new clades (namely clades New 1 and New 2). The majority of the isolates were clustered into three clades, clade 6 (37.5%), clade 1 (15.0%) and clade 17 (15.0%). Isolates of clade New 2 were specifically identified in East Asia. We identified three cases of potential nosocomial transmission based on association analysis between patients’ clinical data and the genotypes of corresponding isolates. Finally, by analyzing the genotypes of serial isolates we further demonstrated that the microevolution of C. albicans was due to loss of heterozygosity. Our study represents the first molecular typing of C. albicans in eastern China, and we confirmed that MLST is a useful tool for studying the epidemiology and evolution of C. albicans.

Multilocus sequence typing of Candida albicans isolates from the oral cavities of patients undergoing haemodialysis

“…Similarly, these clades contain the fewest strains in the global C. albicans MLST database. No isolates in Clade 13 were found in studies from Chinese regions such as Beijing 37 , Chengdu 38 , Shanghai 39 , 40 , Shenyang 41 , and Taiwan 42 – 44 . Several earlier studies found strong evidence for a geographic influence in the low representation of some clades in certain regions of the world.…”

“…In the global database, most Clade 19 isolates were from Asian subjects (China, South Korea, Iran, Kuwait). This clade was first described as clade New 1 by Wu 40 in Shanghai, China.…”

Investigating Clinical Issues by Genotyping of Medically Important Fungi: Why and How?

“…The main source of invasive C. albicans was confirmed to originate from the endogenous mycobiota (6,130,140,141). Indeed, identity between isolates from blood and colonized anatomical sites was almost always observed, leading to the conclusion that nosocomial transmission between patients is likely a rare event (141,142), even if an outbreak is suspected (143), although some authors have reported nosocomial transmission in hospital environments (144)(145)(146)(147)(148). MLP typing has also been used to track the origin of graft site candidiasis after kidney transplantation (149).…”

Genotype and homology analysis of pathogenic and colonization strains of Candida albicans from hospitalized neonates

“…12 Some STs were the same among isolates from different patients, supporting nosocomial transmission among patients. 10,16 The differences in the number of STs identified in this study compared to other studies may have been the result of different geographic regions. 26,27 Moreover, the differences in the STs identified among the isolates from Shenzhen People's Hospital and other Chinese hospitals 10,15 suggest that the genetic complexity is different among the communities of C. albicans in different hospitals.…”

“…9 Molecular biology typing methods, such as MLST and MLVA, are very useful for epidemiological investigation and nosocomial infection surveillance of C. albicans in hospital wards. 10 Indeed, MLST is performed easily and can be used to group C. albicans isolates in a similar way to Ca3 Southern hybridization. 11 It has been used to study the geographic distribution, 12e14 population structure, 13 infection regions, 15 prevalence, 15 diversity, 16 microevolution, 10,16 genetic basis of pathogenicity, 17 and drug resistance 13,18 of C. albicans.…”