MALDI-TOF MS identification of Malassezia species isolated from patients with pityriasis versicolor at the seafarers' medical service in Dakar, Senegal

Abstract

Pityriasis versicolor (PV) is a superficial mycosis caused by yeast of the genus Malassezia. The most common isolated Malassezia species in PV lesions differ among M. furfur, M. globosa and M. sympodialis. We purpose to determine the distribution of Malassezia species in PV patients at the seafarers' medical service in Dakar, Senegal and to examine whether any association between identified Malassezia species and patients' profile. From May 2017 to August 2017, first a questionnaire was filled to get informative data before collection of skin scrapings taken from most scaly site using sterile scalpel blade and application of scotch^® for direct examination (DE). At the laboratory, DE, culture and identification by MALDI-TOF MS were done. One hundred patients with PV - all men - were included with a mean age of 34 years. Among seafarers, 81% were sailors. Clinical prevalence of PV was highest in aged adults patients with ages of 31 to 60 years (56%). Seafarers with high level of education were less representative with only 2%. The mean duration of the PV was 26.83 months. 20% of subjects suffered lesions in more than one location. The chest was the most affected anatomical site. Furthermore, possible predisposing factors associated with PV were also detected. DE was positive in 95% but culture growth only in 46%. MALDI-TOF MS analysis of the positive cultures could be performed in 84.8% (39/46). Only M. furfur was identified in 100% (39/39). In definitive, M. furfur is the only causative agent of PV in Dakar.

Keywords: MALDI-TOF MS; Malassezia; Pityriasis versicolor; Seafarer; Senegal.