Genotyping of Malassezia species from seborrheic dermatitis/dandruff patients

Abstract S9.5 Malassezia: pathogenesis and disease, September 23, 2022, 4:45 PM - 6:15 PM Objectives Seborrheic dermatitis/dandruff (SD/D) are common chronic inflammatory skin disorders characterized by recurrent greasy scales with erythema and itchiness. Malassezia lobose and M. restricta are the predominant agents associated with SD/D. The aim of the study was to differentiate Malassezia strains causing SD/D from commensal using a highly discriminatory DNA fingerprinting technique, Fluorescent Amplified Fragment Length Polymorphism (FAFLP). Methods A total of 154 (M. globosa, n = 85; M. restricta, n = 55; M. arunalokei, n = 14; standard strains, n = 3) isolates from SD/D patients and healthy controls were analyzed using FAFLP. DNA sample was digested with restriction enzymes EcoRI and HindIII, and the fragments were linked to prepared adapters. Pre-selective followed by selective amplification reactions were performed using EcoRI-AC [6-carboxyfluorescein (6-FAM) labeled] and HindIII-T selective primers. The similarity coefficient was determined by Pearson correlation with negative similarities clip to zero. The densitometric curve cluster analysis was performed by unweighted pair group method with arithmetic means using Bionumerics software. The similarity co-efficient of 70% was taken as a cut-off. Results M. restricta and M. arunalokei isolates had a similarity co-efficient of 20%, whereas it was 50% among M. restricta and 60% among M. arunalokei isolates (Fig. 1). Majority of the isolates (n = 38.69%) clustered to form FAFLP type-I, followed by type-II (n = 14.25%), and type-III (n = 3.6%). All three FAFLP types formed tight clustering among themselves (>80% similarity co-efficient) showing less genetic diversity within each FAFLP type. Type-II clustered strains were isolated from the scalp of SD/D patients (P <.05). M. arunalokei isolates were clustered into two FAFLP types (P = .05). All FAFLP type-I isolates (n = 10,71%) were from the scalp of moderate and severe SD/D patients, whereas all type-II isolates (n = 4,29%) were from nasolabial folds of either SD/D patients or healthy controls. All 11 FAFLP types of M. globosa formed very loose structured cluster showing high genetic diversity in intra and inter-FAFLP types (Fig. 2). Majority of the isolates (n = 63,74%) clustered to form FAFLP type-II, followed by type X (n = 5.6%), type-I (n = 4.5%), type-III (n = 3.3.5%), type-IV (n = 3.3.5%), type-V (n = 2.2%), type-VIII (n = 2.2%), and type-VI, VII, IX, XI (n = 1.1% each). No geographic specific isolate clustering was observed in FAFLP. Conclusion M. restricta type-II and M. arunalokei type-I strains were isolated only from the scalp of moderate to severe forms of SD/D. However, no such severity-specific clustering was observed in M. globosa. The results strongly suggest the role of certain genotypes of M. restricta and M. arunalokei in the causation of SD/D.