Dermatology and Venereology Department, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt.
Dermatology and Venereology Department, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt.
J Mycol Med. 2022 Nov;32(4):101301. doi: 10.1016/j.mycmed.2022.101301. Epub 2022 Jun 7.
The genus Malassezia represents the dominant eukaryotic component of the skin microbial flora. There are complex interactions between this commensal and the skin, leading to various Malassezia-caused or Malassezia exacerbated skin conditions.
To identify Malassezia species in lesions of patients with pityriasis versicolor (PV), atopic dermatitis (AD), and seborrheic dermatitis (SD), as well as corresponding sites in healthy subjects according to the culture methods used for Malassezia species isolation.
Scrapings were collected from 80 patients (40 PV, 20 AD, and 20 SD) and 30 healthy subjects. For 10-14 days, specimens were cultured on Dixon's medium and Malt extract agar. Direct microscopic examination with Gram's stain, subculture on Hi chrome agar, Dixon's medium at various temperatures, Tweens assimilation, and hydrolysis of tryptophan were used for the identification of yeast isolates.
The isolation frequency of Malassezia species in healthy subjects was 13.3% for M. furfur, 10.0% for M. globosa, and 3.3% for M.sympodialis. In patients with SD, M. furfur was isolated more frequently from scalp lesions (25.0%) and then M. sympodialis (15%) and M. globosa (10%). Malassezia sympodialis was the most prevalent isolated species in AD lesions (20%), followed by M. furfur (10%). Malassezia species isolation was found to be most prevalent in PV lesions, with M. furfur being the most prevalent identified species (52.5 %), followed by unidentified species (20%).
Malassezia species composition was similar in PV, SD, and healthy subjects, with M. furfur being the commonest isolate, while Malassezia sympodialis was the prevalent species isolated in AD lesions. Chrome agar media can be promising for the identification of Malassezia species phenotypically. However, species differentiation has to be complemented by molecular methods.
马拉色菌属是皮肤微生物菌群中主要的真核成分。这种共生菌与皮肤之间存在着复杂的相互作用，导致了各种马拉色菌引起或加重的皮肤状况。
根据马拉色菌属分离培养方法，确定花斑癣（PV）、特应性皮炎（AD）和脂溢性皮炎（SD）患者皮损及健康对照者相应部位的马拉色菌属种。
采集 80 例患者（40 例 PV、20 例 AD 和 20 例 SD）和 30 例健康对照者的皮损标本。标本在 Dixon 培养基和麦芽浸膏琼脂上培养 10-14 天。用革兰氏染色直接镜检、Hi chrome 琼脂、不同温度的 Dixon 培养基、吐温同化和色氨酸水解进行酵母分离物的鉴定。
健康对照者中马拉色菌属种的分离频率为糠秕马拉色菌 13.3%、球形马拉色菌 10.0%和合轴马拉色菌 3.3%。SD 患者头皮皮损中分离出更多的糠秕马拉色菌（25.0%），然后是合轴马拉色菌（15%）和球形马拉色菌（10%）。马拉色菌属种在 AD 皮损中最常分离到的是合轴马拉色菌（20%），其次是糠秕马拉色菌（10%）。PV 皮损中马拉色菌属种的分离最为普遍，糠秕马拉色菌是最常见的鉴定种（52.5%），其次是未鉴定种（20%）。
PV、SD 和健康对照者的马拉色菌属种组成相似，糠秕马拉色菌最常见，而合轴马拉色菌是 AD 皮损中最常见的分离种。铬琼脂培养基对马拉色菌属种的表型鉴定有一定的应用前景，但种间差异还需要通过分子方法来补充。
