Abstract: Objective To investigate the colonization and the species identification of Malassezia yeasts in skin of the patients with pruritus of unknown origin (PUO) in the Marine corps in southern China. The purpose of our study was to evaluated the relationship between Malassezia microflora and PUO.Methods The samples collected from the skin of 56 cases of patients with PUO and 50 healthy controls were detected by direct microscopic examination using Crystal violet staining and were cultured using rapeseed oil medium.The yeasts isolated were identified by their morphological and bio-physiological properties according to Guillot et al method.Results In both observation and control groups, the positive rate of direct microscopic examination were respectively 74.10% and 72.00%, No statistical difference was observed (χ²=0.344, P >0.05) between the two groups. However, the positive rate of the colonization density of Malassezia spores at level III-IV (Per 10 HPF≥50-100 spores) in the observation group were significantly higher than it in the control group. (were respectively 74.70 % and 38.89%, χ²=20.30, P <0.05). Four Malassezia species were identified from 143 isolates obtained from the observation group, the positive rate were 85.12% (143/168), in which 97 isolates were identified as M.sympodialis (67.83%), 26 isolates were M.globosa (18.18%), and 19 isolates were M.furfur (13.29%), and 1 isolates were M.obtuse (0.70%). Four Malassezia species were identified from 107 isolates obtained from the control group, the positive rate were 71.33%, in which 55 isolates were identified as M.furfur (51.40%), 33 isolates were M.sympodialis (30.84%), 14 isolates were M.globosa (13.08%), and 5 isolates were M.obtuse (4.67%) . The identification rate and distribution of Malassezia yeasts in the skin were significantly different between the two groups (χ²=2.99, P<0.01 and χ²=51.16, P <0.01, respectively).Conclusion The colonization density of Malassezia yeasts in the observation group were significantly higher than it in the control group.M.sympodialis is the major species of Malassezia microflora found in the observation group.

Key words: PUO, Malassezia, colonization, culture