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Research Article

Identification and antifungal susceptibility of a large collection of yeast strains isolated in Tunisian hospitals

, , , &
Pages 737-746 | Received 22 Nov 2012, Accepted 24 Apr 2013, Published online: 14 Jun 2013
 

Abstract

In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a rapid method to identify yeasts isolated from patients in Tunisian hospitals. When identification could not be exstablished with this procedure, sequencing of the internal transcribed spacer with 5.8S ribosomal DNA (rDNA) (ITS1–5.8S–ITS2) and D1/D2 domain of large-subunit (LSU rDNA) were employed as a molecular approach for species differentiation. Candida albicans was the dominant species (43.37% of all cases), followed by C. glabrata (16.55%), C. parapsilosis (13.23%), C. tropicalis (11.34%), C. dubliniensis (4.96%), and other species more rarely encountered in human diseases such as C. krusei, C. metapsilosis, C. lusitaniae, C. kefyr, C. palmioleophila, C. guilliermondii, C. intermedia, C. orthopsilosis, and C. utilis. In addition, other yeast species were obtained including Saccharomyces cerevisiae, Debaryomyces hansenii (anamorph known as C. famata), Hanseniaspora opuntiae, Kodamaea ohmeri, Pichia caribbica (anamorph known as C. fermentati), Trichosporon spp. and finally a novel yeast species, C. tunisiensis. The in vitro antifungal activities of fluconazole and voriconazole were determined by the agar disk diffusion test and Etest, while the susceptibility to additional antifungal agents was determined with the Sensititre YeastOne system. Our results showed low incidence of azole resistance in C. albicans (0.54%), C. tropicalis (2.08%) and C. glabrata (4.28%). In addition, caspofungin was active against most isolates of the collection with the exception of two K. ohmeri isolates. This is the first report to describe caspofungin resistant isolates of this yeast.

Acknowledgements

The authors thank technical help of F. Ischer. JE was supported by a grant of the Swiss Confederation. The authors also acknowledge the contribution of Ridha Khelifa and Saïda Zouari (Service des laboratoires, CHU Habib Thameur), Kacem Mahdouani (Laboratoire de Bactériologie, Hôpital Ibn El Jazzar de Kairouan), Dalenda El Euch (Service de Dermatologie, CHU La Rabta) and Emna Chaker (Laboratoire de parasitologie-mycologie, CHU La Rabta) for sampling of yeast isolates and Luis André Vale Silva (Institute of Microbiology, CHUV, Lausanne, Switzerland) for reading the manuscript.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and the writing of the paper.

This paper was first published online on Early Online on 10 June 2013.

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