Analysis of the Clonality of Candida tropicalis Strains from a General Hospital in Beijing Using Multilocus Sequence Typing

PLOS ONE, Dec 2019

Multilocus sequence typing (MLST) based on six loci was used to analyze the relationship of 58 Candida tropicalis isolates from individual patients in a general hospital in Beijing, China. A total of 52 diploid sequence types (DSTs) were generated by the MLST, all of which were new to the central database. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrograms were constructed, which showed that the 58 isolates were distributed robustly and 6 main groups were clustered regardless of the specimen source and medical department. The minimum spanning tree (MST) of the 58 isolates (52 DSTs) and all 401 isolates (268 DSTs) in the C. tropicalis central database (http://pubmlst.org/ctropicalis/) indicated that the isolates in this study clustered in three relative pure clonal complexes, and 2 clustered with isolates from Taiwan, Belgium, Brazil, and the US. This study presents the first MLST analysis of C. tropicalis isolates from Mainland China, which may be useful for further studies on the similarity, genetic relationship, and molecular epidemiology of C. tropicalis strains worldwide.

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Analysis of the Clonality of Candida tropicalis Strains from a General Hospital in Beijing Using Multilocus Sequence Typing

et al. (2012) Analysis of the Clonality of Candida tropicalis Strains from a General Hospital in Beijing Using Multilocus Sequence Typing. PLoS ONE 7(11): e47767. doi:10.1371/journal.pone.0047767 Analysis of the Clonality of Candida tropicalis Strains from a General Hospital in Beijing Using Multilocus Sequence Typing Yuan Wu 0 Haijian Zhou 0 Jing Wang 0 Lianqing Li 0 Wenge Li 0 Zhigang Cui 0 Xia Chen 0 Ruiqi Cen 0 Jinxing Lu 0 Ying Cheng 0 Wenjun Li, Duke University Medical Center, United States of America 0 1 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention , Beijing, People's Republic of China, 2 China- Japan Friendship Hospital , Beijing , People's Republic of China, 3 Shanxi Center for Clinical Laboratories , TaiYuan, Shanxi , People's Republic of China, 4 Department of Critical Care Medicine, Fu Xing Hospital, Capital Medical University , Beijing , People's Republic of China Multilocus sequence typing (MLST) based on six loci was used to analyze the relationship of 58 Candida tropicalis isolates from individual patients in a general hospital in Beijing, China. A total of 52 diploid sequence types (DSTs) were generated by the MLST, all of which were new to the central database. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrograms were constructed, which showed that the 58 isolates were distributed robustly and 6 main groups were clustered regardless of the specimen source and medical department. The minimum spanning tree (MST) of the 58 isolates (52 DSTs) and all 401 isolates (268 DSTs) in the C. tropicalis central database (http://pubmlst.org/ctropicalis/) indicated that the isolates in this study clustered in three relative pure clonal complexes, and 2 clustered with isolates from Taiwan, Belgium, Brazil, and the US. This study presents the first MLST analysis of C. tropicalis isolates from Mainland China, which may be useful for further studies on the similarity, genetic relationship, and molecular epidemiology of C. tropicalis strains worldwide. - With the increasing number of immunocompromised patients, long-term hospitalized patients, and invasive medical inspection and therapy, the genus Candida has emerged as a major group of opportunistic pathogens that cause superficial and invasive infections in humans [15]. Candida is considered the fourth most commonly isolated organisms from nosocomial bloodstream infections in United States and sixth in Europe [610]. The invasive infections caused by Candida species are associated with significant morbidity and mortality [5,11,12]. Although Candida albicans accounts for the majority of infections, other non-albicans Candida species such as Candida tropicalis have increasingly been recognized as pathogens for these types of infections. C. tropicalis is considered the leading pathogen in nosocomial fungemia and hepatosplenic fungal infections in patients with cancer, especially leukemia [13,14]. C. tropicalis is the second most frequently isolated non-albicans pathogen in the Asia-Pacific region and in Brazil [15,16]. In large independent epidemiologic surveys, the isolation rate of C. tropicalis from blood is 5% to 30% [17,18]. In evolutionary terms, it is closely related to C. albicans [1921]. Previous studies conducted in Asia show the frequency of fluconazole resistance in the intermediate C. tropicalis strains, which was originally found in Candida glabrata that displayed natural resistance to fluconazole [22,23]. Furthermore, a high proportion of C. tropicalis isolates has exhibited low susceptibility to flucytosine [24,25]. Numerous molecular typing methods have been used to determine the molecular epidemiology and resistance of C. tropicalis, such as MLST (multilocus sequence typing). MLST is a useful tool in population analysis within a species [20,26]. The MLST data is comparable among labs worldwide via the central database in the Internet (http://www.mlst.net/), and it satisfies the increasing need for global surveillance [27]. The MLST approach reveals different geographical origins, anatomic sources, and other characteristics between clades of closely related isolates [20]. MLST has been developed for C. albicans and C. glabrata [2830], which offers further information regarding strain variations, including maintenance, replacement, and microevolution in the host [27]. The MLST system for C. tropicalis, which comprises six housekeeping genes (ICL1, MDR1, SAPT2, SAPT4, XYR1 and ZWF1a), has been described by Tavanti et al. in 2005 [24]. The aim of our study is to examine the clonality of C. tropicalis by performing successive strain collection for one year in a general hospital in Beijing, China, and to ascertain whether factors such as hospital department origin, anatomic source, and so on are related to certain specific MLST diploid sequence types (DSTs) types. Furthermore, the cor (...truncated)


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Yuan Wu, Haijian Zhou, Jing Wang, Lianqing Li, Wenge Li, Zhigang Cui, Xia Chen, Ruiqi Cen, Jinxing Lu, Ying Cheng. Analysis of the Clonality of Candida tropicalis Strains from a General Hospital in Beijing Using Multilocus Sequence Typing, PLOS ONE, 2012, 11, DOI: 10.1371/journal.pone.0047767