Pityriasis versicolor: isolation and identification of the main species

Abstracts

As espécies do gênero Malassezia isoladas foram: Malassezia sympodialis (16,66%), Malassezia furfur (12,50%), Malassezia globosa (11,45%) e Malassezia slooffiae (2,10%). A Malassezia sympodialis foi a espécie que predominou em nosso estudo. As espécies de Malassezia identificadas não mostraram correlação com as variantes clínicas e com a distribuição das lesões de pitiríase versicolor quanto às regiões do corpo.

Isolamento; Levedura; Malassezia; Pitiríase

COMMUNICATION

Pityriasis versicolor: isolation and identification of the main species of Malassezia

Valéria Maria de Souza Framil^I; Márcia S. C. Melhem^II; Maria Walderez Szeszs^III; Elaine Cristina Corneta^IV; Clarisse Zaitz^V

^IPhysician, Ph.D., at the Dermatology Clinic of Irmandade da Santa Casa de Misericordia de Sao Paulo - São Paulo (SP), Brazil

^IILevel IV Scientific Researcher at Instituto Adolfo Lutz - Sao Paulo (SP), Brazil

^IIIScientific Researcher at Instituto Adolfo Lutz - Sao Paulo (SP), Brazil

^IVMaster's degree student in Microbiology/ICB-USP with a scholarship from CAPES - Coordination for the Improvement of Higher Education Personnel - Sao Paulo (SP), Brazil

^VProfessor, Ph.D., at the Dermatology Clinic of Irmandade Misericordia da Santa Casa de Sao Paulo - São Paulo (SP), Brazil

^{Mailing Address}

ABSTRACT

Species of the genus Malassezia isolated were: Malassezia sympodialis (16.66%), Malassezia furfur (12.50%), Malassezia globosa (11.45%), and Malassezia slooffiae (2.10%). Malassezia sympodialis predominated in the study. The species of Malassezia identified did not show correlation with clinical variants and with the distribution of pityriasis versicolor lesions in relation to areas of the body.

Keywords: Isolation; Malassezia; Pityriasis; Yeast

In 1996, Gheho et al. studied the biochemical, morphological and molecular characteristics of species of Malassezia and described seven species currently involved in pityriasis versicolor: Malassezia furfur, Malassezia sympodialis, Malassezia globosa, Malassezia obtusa, Malassezia restrita, Malassezia sloofiae, and Malassezia pachydermatis. The objective of this study was to identify species of Malassezia and correlate them with clinical variants and the distribution of pityriasis versicolor lesions in relation to areas of the body.

The study protocol and its informed consent forms have been approved by the Research and Ethics Committee of Irmandade Santa Casa de Misericordia de Sao Paulo. The 102 cases of pityriasis versicolor were confirmed by means of clinical and mycological diagnosis. The following clinical variants of pityriasis versicolor were determined: hypochromic, hyperchromic, combination of hypochromic and hyperchromic, erythematous, follicular, and circinate lesions. The distribution of pityriasis versicolor lesions in areas of the body was classified into three groups: 1- Light: involvement of only one area of the body (neck; anterior or posterior thoracic region); 2- Moderate: involvement of more than one and of three or fewer areas of the body (anterior + posterior thoracic regions + abdominal region; anterior + posterior thoracic region + dorsal region; anterior thoracic region + arms L + R; anterior + posterior thoracic region + neck; forearms L or R; abdominal region + dorsal region); 3- Disseminated: involvement of more than three areas of the body (neck + trunk + UL + LL + axillas + groin region).

Of the 102 patients studied, only biological samples of 96 were sent for identification of species of Malassezia, since 6 were lost. Biological samples of 96 cases were processed in the Mycology Section of Instituto Adolfo Lutz. The culture medium used was modified Dixon's agar (Van Abbe, 1964) and incubation for the isolation of colonies was done in sterilizer at 32°C for a maximum of 15 days. Catalase, Tween assimilation, and esculin were the biochemical tests used for the identification of species of Malassezia.² Polymerase chain reaction and restriction fragment length polymorphism analysis (PCR-RFLP) was the molecular method used to confirm the identification of species.³ Data were stored in a database and compared using the Chi-square and the Fisher tests. Values of p < 0.05 were considered statistically significant.

The clinical variant of hypochromic maculae was found with a frequency of 94.11%; hyperchromic maculae, 0.98%; combination of hypochromic and hyperchromic maculae, 0.98%; erythematous maculae, 1.96%; follicular lesions, 0.98%, and circinate lesions, 0.98%.

The distribution of pityriasis versicolor lesions in relation to areas of the body was classified as: light (23.52%); moderate (56. 86%), and disseminated (19.60%). Regarding the identification of species of Malassezia, as an etiologic agent of pityriasis versicolor, it was observed that Malassezia sympodialis had a frequency of 16.66%; Malassezia furfur, 12.50%, Malassezia globosa, 11.45%, and Malassezia slooffiae, 2.10%. The percentage of cultures with negative results was 57.29%. (Table 1) shows species of Malassezia isolated in relation to the clinical variants of pityriasis versicolor. (Table 2) indicates species of Malassezia isolated in relation to the distribution of pityriasis versicolor lesions in areas of the body.

The hypochromic variant is the classical clinical variant cited more often in the literature. Its higher frequency was also confirmed in this study. Studies in the literature state that probably due to sun exposure in tropical countries, the hypochromic variant has had its incidence increased.^6,7,9,10 Other clinical variants such as erythematous lesions, hyperchromic lesions, combination of hypochromic and hyperchromic lesions, follicular lesions, and circinate lesions were also found with low frequency in other studies in the literature.^7,10 The correlation between species of Malassezia and the clinical variants of pityriasis versicolor was not significant (p < 0.05).

Species of Malassezia are part of the normal skin microbiota and are generally found in the pilous follicles of seborrheic areas. In the presence of lipids, yeast transforms into its parasite form like pseudohyphae. ⁹ In this study, most patients showed moderate (56.86%) and disseminated (19.6%) distribution of pityriasis versicolor lesions in areas of the body. In other words, presence of the parasite forms of species of Malassezia in seborrheic and non-seborrheic areas was observed. The relation between species of Malassezia and the distribution of pityriasis versicolor lesions in areas of the body remains unclear. It was not possible to establish a correlation between the two with the statistical tests employed (p < 0.05).

The high frequency of negative cultures found in the study is due to two main factors: the best culture medium, not yet standardized for the isolation of species of Malassezia, and the length of time between collection of clinical material and its cultivation. Recovery of species of Malassezia occurs in less than 50% of the cases, despite the use of specific culture media to optimize yeast isolation .⁸ The predominance of M. sympodialis as etiologic agent of pityriasis versicolor in this study contradicts an old belief that the only etiologic agent responsible for causing pityriasis versicolor was M. furfur. It was not possible to establish a correlation between species of Malassezia, clinical variants, and the distribution of pityriasis versicolor lesions in areas of the body.

REFERENCES

Recebido em 10.06.2008.

Aprovado pelo Conselho Consultivo e aceito para publicação em 27.11.09.

Conflict of interest: None

Financial support: None

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• 9. Zaitz C, Ruiz LRB, Souza VM. Dermatoses associadas às leveduras do gênero Malassezia. An Bras Dermatol. 2000;75:129-42.
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*

Study conducted at the Dermatology Clinic of Irmandade da Santa Casa de Misericordia de São Paulo and Mycology Division of Instituto Adolfo Lutz - São Paulo (SP), Brazil.

Publication Dates

• Publication in this collection
  06 May 2010
• Date of issue
  Feb 2010

History

• Received
  10 June 2008
• Accepted
  27 Nov 2009