P31-HEALTHY HUMAN DISTAL GUT MICROBIOTA IN TUNISIA: ISOLATION AND IDENTIFICATION OF YEAST CANDIDA GENUS WHICH COLONIZE THE INTESTINE

• Published in: Archives de l'Institut Pasteur de Tunis Vol. 95; no. 1/2; pp. 77 - 78
• Main Authors: Rhouma, K Ben, Feki, S, Abda, I Ben, Boulehmi, N, Zallega, N, Gangneux, J-P, Bouratbine, A
• Format: Journal Article
• Language: English
• Published: Tunis Institut Pasteur de Tunis 01.01.2018
• Subjects: Amphotericin B; Candida; Candida krusei; Chloramphenicol; Colonies; Digestive system; Environmental factors; Feces; Fluconazole; Gastrointestinal tract; Gentamicin; Intestinal microflora; Mass spectroscopy; Micafungin; Microbiota; Microorganisms; Species; Yeast
• ISSN: 0020-2509; 2233-2189

Introduction: Human gut microbiota is a complex ecosystem. It is composed by several different commensal microorganisms such as Bacteria, Archaea, and Eukarya. The Candida genus, which is represented by different species, is by far the most represented yeast in the community of intestinal fungi. Objective: The aim of this study is to identify Candida species isolated from the stool of healthy individuals by using different culture-dependent methods. Materials and Methods: In this study, we analyzed Candida species present in 46 fecal samples provided by healthy persons. The age average of these subjects is between 20 and 40 years. The fecal samples were firstly spread-plated on Sabouraud Dextrose Agar supplemented with Chloramphenicol or with Chloramphenicol and Gentamicin. A total number of 63 yeast isolates were obtained. In a first approach, the isolates, which have an aspect of Candida colonies, were tested on BBL CHROMagar Candida medium for a primary identification. This media is able to distinguish between different species of the genus Candida by the colonies coloration (Candida albicans and C. dubliniensis, C. tropicalis, C krusei). The other yeast isolates (non-Candida genus) were characterized by using biochemical test (ID 32C, Biomerieux). The 63 yeast isolates were analyzed by the mass spectrometry MALDI-TOF to confirm the results of the first identification with the CHROMagar. For the 56 yeast isolates, the in vitro antifungal activities of fluconazole were determined using the RPMI supplemented with fluconazole (4mg/L) while the sensitivity to amphotericin В and micafungin was determinate by E-test. Results: It appears that only 37 stool samples from 46 (80%) contain cultivable Fungi (we excluded three samples contaminated by molds). The analyses by the CHROMAgar and the MALDI-TOF showed approximatively the same results. Although, the last method gave a best distinction between (C. albicans and C. dubliniensis). Our results showed that from the 63 yeasts isolates, C. albicans was predominant (36%), followed by C. glabrata, C. krusei, C. parapsilosis (16%), C. kefyr, C. tropicalis, Candida ethanolica, Candida dubliensis 2%). Other yeast species were also identified: Geotrichum capitatum (4%), Rhodotorula mucilaginosa and Trichsporon asahii (2%). The sensitivity to fluconazole is observed for all isolates except for C. krusei, which is naturally resistant. However, they were all sensitive to micafungin (CMI<2µg/ml) and amphotericin B (CMI ≤1µg/ml). Conclusion: The composition of gut fungal communities is variable and differs from an individual to another. It is influenced by diet and other environmental factors. The use of the MALDI-TOF method to identify the yeast isolates is efficient because it is fast and reliable.