Molecular and Phenotypic Identification and Speciation of Malassezia Yeasts Isolated from Egyptian Patients with Pityriasis Versicolor

Abstract

Introduction: Pityriasis Versicolor (PV) is a common health problem caused by genus Malassezia, a lipophilic fungi found as a part of the normal flora of skin. Although PV is common in Egypt, there is little information regarding the Malassezia species distribution in PV patients to date. Aim: To spot a light on the distribution and clinico-epidemiological features of the Malassezia species in PV patients and healthy individuals that were established by conventional phenotypic and molecular techniques. Materials and Methods: A cross-sectional study including 167 individuals; 137 clinically suspected PV patients attending Mansoura University Hospitals, Egypt and 30 healthy control individuals, was carried out. Characterization of Malassezia species was performed phenotypically by conventional, culture-based methods and biochemical tests. Genomic DNA was extracted from isolated colonies for PCR amplification of the highly conserved 26S rDNA region with further species level identification by Restriction Fragment Length Polymorphism (RFLP) using Hha1 and BstC1 enzymes. The association of Malassezia species with epidemiological profile and clinical characteristics was studied. Results: A 94.2% of PV samples and 13.3% of control samples were positive by Potassium Hydroxide (KOH) while 71.5% of PV samples and 16.7% of control samples yielded growth in culture with high statistically significant differences (p=0.0001, for both methods). By phenotypic methods, only 75.5% of isolates from patients were identified as: M. furfur (51.4%), M. globosa, (29.7%), M. restricta (13.5%) and M. pachydermatis (5.4%) while by RFLP technique, six species were revealed: M. furfur (44.9%), M. globosa (24.5%), M. sympodialis (12.2 %), M. restricta (10.2%), M. obtusa (4.1%) and M. pachydermatis (4.1%). Most species were isolated from hypopigmented lesions of PV patients aged between 20-29 years. Neck and back were the most common affected sites. Only M. furfur (10%) and M. globosa (6.7%) were identified in healthy controls. Conclusion: M. furfur and M. globosa are the commonly encountered species in both healthy and diseased human skin although other species were identified in PV patients. PCRRFLP method represents a considerably accurate technique in identification of different Malassezia species for better understanding of their effect on the clinico-epidemiological characterization of PV patients in Egypt.

Keywords

• lipophilic yeasts
• pcr-restriction fragment length polymorphism
• tinea versicolor