Molecular identification of uncommon clinical yeast species in Iran.

Hossein Mirhendi,Ladan Karimi,Rasoul Mohammadi,Hossein Khodadadi

doi:10.18869/acadpub.cmm.1.2.1

Abstract

Background and Purpose:By using advanced detection/identification methods, the list of emerging uncommon opportunistic yeast infections is rapidly expanding worldwide. Our aim in the present study was sequence-based species delineation of previously unidentified yeasts obtained from a clinically yeast collection.Materials and Methods:A total of twenty three out of the 855 (5.7%) yeast isolates which formerly remained unidentified by PCR-RFLP method, were subjected to sequence analysis of the entire internal transcribed spacers (ITS) regions of rDNA. The precise species recognition was performed by the comparison of the sequences with the reliable GenBank database.Results:Sequencing analysis of the ITS region of the strains revealed several uncommon yeasts that were not reported previously in Iran. The species include Hanseniaspora uvarum, Saccharomyces cerevisiae, Sporidiobolus salmonicolor, Pichia fabianii, Pichia fermentans, Candida famata, Candida inconspicua, Candida maqnoliae, Candida guilliermondii, Candida kefyr, Candida rugosa, Candida lusitaniae, Candida orthopsilosis, and Candida viswanathii.Conclusion:We identified several rare clinical isolates selected from a big collection at the species level by ITS-sequencing. As the list of yeast species as opportunistic human fungal infections is increasing dramatically, and many isolates remain unidentified using conventional methods, more sensitive and specific advanced approaches help us to clarify the aspects of microbial epidemiology of the yeast infections.

Highlights

Among hundreds of yeast species, only a few may colonize mucocutaneous membranes of healthy individuals and in specific circumstances they can cause opportunistic infections in immunocompromised patients [1]
Among the 855 yeast strains which were previously isolated from patients with various forms of fungal infections and identified by polymerase chain reaction (PCR)-RFLP, a total of 23 yeasts were classified as uncommon yeast species, and none of them showed a specific color of dominant yeasts on Chromogenic plates
We found six new yeast species which have not reported in Iran so far, including two strains of Hanseniaspora uvarum, one strain of Pichia fabianii, one Sporidiobolus salmonicolor, one Pichia fermentans and one Candida magnolia

Summary

Introduction

Among hundreds of yeast species, only a few may colonize mucocutaneous membranes of healthy individuals and in specific circumstances they can cause opportunistic infections in immunocompromised patients [1]. The frequency of these species is uncommon or rare; it is possible that after antifungal controlling of more susceptible species, they become more frequent in the future. These emerging yeast species can cause severe opportunistic infections in predisposed hosts [3,4]. By using advanced detection/identification methods, the list of emerging uncommon opportunistic yeast infections is rapidly expanding worldwide. As the list of yeast species as opportunistic human fungal infections is increasing dramatically, and many isolates remain unidentified using conventional methods, more sensitive and specific advanced approaches help us to clarify the aspects of microbial epidemiology of the yeast infections.

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Conclusion