Morphological and molecular identification of the oral thrush fungi isolated from immunocompromised patients at the clinical haematology unit, internal medicine department, Mansoura University, Egypt.

Background: A significant increase in human infections by Candida spp. was observed in the last decades. Therefore, the objective was to evaluate the prevalence, conventional, and molecular identification of Candida species infecting leukemia patients. Methods: Twenty-five patients, ages 20 to 65, participated in this study. Samples were obtained by swabbing the oral cavity of oral thrush patients. The isolates were identified by their growth characteristics on SDA, CHROMagarTM Candida, formation of chlamydospores, germ tube, and DNA extraction. Results: 12 male cases (48%), with the highest percentage (16%) between males aged 40 to 49. Thirteen infected females (52%) with the highest percentage (20%) aged 50 to 65y. The relationship between patient gender and infection rate is significant. The species were identified as Candida albicans and Pichia kudriavzevii through growth on CHROMagarTM Candida by the formation of green for C. albicans and a light pink colour for P. kudriavzevii at 45 °C. Chlamydospore and germ tube formation increased differentiation and confirmation of C. albicans. The genomic DNA was extracted from 3 strains, the rDNA-ITS region was amplified and sequenced, and phylogenetic trees were constructed. The isolates were accessed in the genebank as C. albicans PP664305 and two strains of P. kudriavzevii (MG-2 & MG-3) with accession numbers PP664417 and PP664439. P. kudriavzevii infected 24% of the men and 28% of the women, while C. albicans infected 24% of both males and females. Conclusion: Raising awareness among immunocompromised patients. Molecular identification is necessary for the proper identification of Candida spp. ‎