Etiological significance of<i>Pityrosporum orbiculare</i>in tinea versicolor

Keddie, Frances; Shadomy, Smith

doi:10.1080/00362176485190061

Cited by 52 publications

(12 citation statements)

References 7 publications

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“…Burke observed typical structures of M. furfur in a patient experimentally infected with P. orbiculare; she also was able to produce hyphal elements in cultures of this organism (20). Keddie and Shadomy isolated P. orbiculare from scales of patients with pityriasis versicolor in which the presence of M. furfur had been demonstrated by staining and direct microscopic examination (72). Dorn and Roehnert reported that globose cells of P. orbiculare readily converted to hyphal elements in a defined medium (29).…”

Section: Historical Perspectivementioning

confidence: 99%

Human infections due to Malassezia spp

1992

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The genus Malassezia contains three member species: Malassezia furfur and Malassezia sympodialis, both obligatory lipophilic, skin flora yeasts of humans, and Malassezia pachydermatis, a nonobligatory lipophilic, skin flora yeast of other warm-blooded animals. Several characteristics suggest the basidiomycetous nature of these yeasts, although a perfect stage has not been identified. Classically, these organisms are associated with superficial infections of the skin and associated structures, including pityriasis versicolor and folliculitis. Recently, however, they have been reported as agents of more invasive human diseases including deep-line catheter-associated sepsis. The latter infection occurs in patients, primarily infants, receiving parenteral nutrition (including lipid emulsions) through the catheter. The lipids presumably provide growth factors required for replication of the organisms. It is unclear how deep-line catheters become colonized with Malassezia spp. Skin colonization with M. furfur is common in infants hospitalized in neonatal intensive care units, whereas colonization of newborns hospitalized in well-baby nurseries and of older infants is rarely observed. Catheter colonization, which may occur without overt clinical symptoms, probably occurs secondary to skin colonization, with the organism gaining access either via the catheter insertion site on the skin or through the external catheter hub (connecting port). There is little information on the colonization of hospitalized patients by M. sympodialis or M. pachydermatis. Diagnosis of superficial infections is best made by microscopic examination of skin scrapings following KOH, calcofluor white, or histologic staining. Treatment of these infections involves the use of topical or oral antifungal agents, and it may be prolonged. Diagnosis of Malassezia catheter-associated sepsis requires detection of the organism in whole blood smears or in buffy coat smears of blood drawn through the infected catheter or isolation of the organism from catheter or peripheral blood or the catheter tip. Culture of M. furfur from blood is best achieved with Isolator tubes and plating onto a solid medium supplemented with a lipid source. Appropriate treatment of patients requires removal of the infected catheter with or without temporary stoppage of lipid emulsions; administration of antifungal therapeutic agents does not appear to be necessary. Because many patients who develop Malassezia catheter-associated sepsis have severe underlying illnesses, caution must be exercised in attributing all clinical deterioration to Malassezia infection. Our better understanding of how these organisms cause disease awaits the development of a useful typing scheme for epidemiologic studies and further studies on microbial virulence factors and the role of the immune response in pathogenesis.

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Section: Historical Perspectivementioning

confidence: 99%

Human infections due to Malassezia spp

1992

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“…This conclusion is based upon several lines of evidence: (a) by using the proper media, the organisms can be readily cultivated from scrapings of tinea versicolor lesions; (b) the cultured organisms can form germ tubes in culture (6,9,10); (c) specific antisera to cultured P. orbiculare organisms have been found to react with the fungal elements in scrapings of tinea versicolor lesions (11); and (d) experimental tinea versicolor infections have been produced in humans through inoculation of cultured P. orbiculare (12). However, although this organism appears to produce tinea versicolor, it is commonly found on the skin of normal individuals (3,4,9).…”

Section: Introductionmentioning

confidence: 99%

Cell-Mediated Immunity to Pityrosporum Orbiculare in Tinea Versicolor

Sohnle¹,

Lech²

1978

J. Clin. Invest.

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A B S T R A C T Pityrosporum orbiculare, the presumed etiologic agent of tinea versicolor, was cultured in vitro and antigenic extracts prepared from the cultured organisms. Studies with lymphocytes from human cord blood and peripheral blood of guinea pigs demonstrated that such extracts were not mitogenic. Further studies in guinea pigs indicated that the animals could be sensitized by the injection of P. orbiculare extract in Freund's complete adjuvant and that this extract could elicit lymphocyte transformation and delayed skin test responses in sensitized animals.A group of 12 tinea versicolor patients and 15 normal subjects were studied in vitro for cell-mediated immunity to P. orbiculare extract. The majority of the subjects tested in both groups demonstrated positive lymphocyte transformation responses to this extract, as well as to standard mitogens and common microbial antigens. However, lymphocytes from tinea versicolor patients produced significantly less leukocyte migration inhibitory factor activity when stimulated by Candida albicans and P. orbiculare extracts than did lymphocytes from normal subjects. This was also true if only subjects with positive lymphocyte transformation responses to these antigens were considered. Leukocyte migration inhibitory factor responses to streptokinase/streptodornase were not significantly different between the two groups. Therefore, it appears that although both normal subjects and tinea versicolor patients demonstrate prior sensitization to antigens of P. orbiculare, the effector function of lymphocytes from most tinea versicolor patients appears to be impaired in that they produce subnormal amounts of the mediator leukocyte migration inhibitory factor when stimulated with antigenic extracts of this organism.

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“…Malassez 4 subsequently described both oval and round spores in scalp scales from patients with dandruff and in recognition of his discovery the genus Malassezia was described in 1889. 8,9 Studying these organisms has always been challenging as they have proved difficult to culture in the laboratory, with variable survival rates in culture and an absolute requirement for lipid supplements. Sabouraud 6 believed that there was a distinct difference between the yeasts that caused pityriasis versicolor and those on scaly scalps, largely because of the presence of hyphae in the former, even though he recognized that the yeast forms were morphologically similar; he named the cause of scalp scaling Pityrosporum malassezii.…”

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confidence: 99%

Malassezia, dandruff and seborrhoeic dermatitis: an overview

Hay

2011

British Journal of Dermatology

115

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From their original description, fungi of the genus Malassezia (previously Pityrosporum) have been associated with dandruff and seborrhoeic dermatitis. The principle evidence on which this connection was based was that the organisms were present, often in high numbers, on the skin in these conditions and that both responded to treatment that inhibited or destroyed Malassezia yeasts. The availability of new tools such as genomic and proteomic analyses has begun to provide a new insight into the pathogenetic mechanisms involved. New evidence shows the production of specific phospholipases on affected skin sites in dandruff and signalling molecules such as malassezin in seborrhoeic dermatitis. It is still not clear why those individuals and skin sites, prone to either disease, are particularly associated with the presence of these marker molecules but these studies are providing clues to the different ways in which organisms, which are normally commensals, interact with human skin.

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Etiological significance ofPityrosporum orbicularein tinea versicolor

Cited by 52 publications

References 7 publications

Human infections due to Malassezia spp

Human infections due to Malassezia spp

Cell-Mediated Immunity to Pityrosporum Orbiculare in Tinea Versicolor

Malassezia, dandruff and seborrhoeic dermatitis: an overview

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