Malassezia yeasts and pityriasis versicolor

From Skin and Gut to the Brain: The Infectious Journey of the Human Commensal Fungus Malassezia and Its Neurological Consequences

The human mycobiome encompasses diverse communities of fungal organisms residing within the body and has emerged as a critical player in shaping health and disease. While extensive research has focused on the skin and gut mycobiome, recent investigations have pointed toward the potential role of fungal organisms in neurological disorders. Among those fungal organisms, the presence of the commensal fungus Malassezia in the brain has created curiosity because of its commensal nature and primary association with the human skin and gut. This budding yeast is responsible for several diseases, such as Seborrheic dermatitis, Atopic dermatitis, Pityriasis versicolor, Malassezia folliculitis, dandruff, and others. However recent findings surprisingly show the presence of Malassezia DNA in the brain and have been linked to diseases like Alzheimer's disease, Parkinson's disease, Multiple sclerosis, and Amyotrophic lateral sclerosis. The exact role of Malassezia in these disorders is unknown, but its ability to infect human cells, travel through the bloodstream, cross the blood-brain barrier, and reside along with the lipid-rich neuronal cells are potential mechanisms responsible for pathogenesis. This also includes the induction of pro-inflammatory cytokines, disruption of the blood-brain barrier, gut-microbe interaction, and accumulation of metabolic changes in the brain environment. In this review, we discuss these key findings from studies linking Malassezia to neurological disorders, emphasizing the complex and multifaceted nature of these cases. Furthermore, we discuss potential mechanisms through which Malassezia might contribute to the development of neurological conditions. Future investigations will open up new avenues for our understanding of the fungal gut-brain axis and how it influences human behavior. Collaborative research efforts among microbiologists, neuroscientists, immunologists, and clinicians hold promise for unraveling the enigmatic connections between human commensal Malassezia and neurological disorders.

Malassezia-associated skin diseases in the pediatric population

Malassezia are yeast species that commonly colonize healthy skin. However, they have been associated with or implicated in the pathogenesis of numerous skin disorders, particularly in the setting of pediatric populations. In this review, we will focus on several Malassezia-associated skin conditions manifesting in infants, children, and adolescents: pityriasis versicolor, Malassezia folliculitis, infantile and adolescent seborrheic dermatitis, head and neck dermatitis, and neonatal cephalic pustulosis. We examine the literature and provide an overview of these conditions, including clinical presentation in diverse skin colors, diagnosis, risk factors, and treatment and management. Additionally, we summarize and highlight some of the proposed theories on the role of Malassezia spp. in the pathogenesis of these skin conditions.

Pityriasis Versicolor-A Narrative Review on the Diagnosis and Management

This narrative review presents a comprehensive overview of the diagnosis and management of pityriasis versicolor (PV), a common superficial fungal infection caused by the yeast Malassezia. PV is characterised by scaly hypopigmented or hyperpigmented patches, primarily affecting the upper trunk, neck, and upper arms. Regarding commensal interactions, Malassezia utilises nutrient sources without affecting the human host. In cases of pathogenicity, Malassezia can directly harm the host via virulence factors or toxins, or indirectly by triggering damaging host responses. The diagnosis typically relies on recognising characteristic clinical features. Due to the wide variability in its clinical presentation, recognising the differential diagnosis is critical. In this paper, we discuss the clinical differentials, with their dermatoscopic presentation, but also describe a range of helpful diagnostic techniques (microscopy, conventional and ultraviolet-induced fluorescence dermatoscopy, and confocal microscopy). Topical therapies are the primary treatment for PV, encompassing non-specific antifungal agents like sulphur with salicylic acid, selenium sulphide 2.5%, and zinc pyrithione. Additionally, specific topical antifungal medications with either fungicidal or fungistatic properties may also be incorporated into the topical treatment regimen, such as imidazoles, allylamines, and ciclopirox olamine. Systemic therapies might occasionally be used. Patient education and the promotion of good personal hygiene are pivotal to reduce the risk of recurrence. In recurrent cases, particularly during warmer and more humid periods, prolonged prophylaxis with topical agents should be considered.

In Vitro Assessment of Azole and Amphotericin B Susceptibilities of Malassezia spp. Isolated from Healthy and Lesioned Skin

Malassezia yeasts have recently gained medical importance as emerging pathogens associated with a wide range of dermatological and systemic infections. Since standardized methods for in vitro antifungal susceptibility testing have not yet been established for Malassezia spp., related diseases are always treated empirically. As a result, a high rate of recurrence and decreased antifungal susceptibility have appeared. Thus, the aims of the study were to assess and analyze the in vitro susceptibility of Malassezia isolated from pityriasis versicolor (PV) lesions and healthy controls. A total of 58 Malassezia strains isolated from PV patients and healthy controls were tested. In vitro antifungal susceptibility testing was conducted using the CLSI broth microdilution with some modifications. Candida spp. criteria established in accordance with CLSI guidelines were used for data interpretation. Ketoconazole and posaconazole seemed to be the most effective molecules against Malassezia species. However, considerable percentages of itraconazole, fluconazole, and amphotericin B ‘‘resistant’’ strains (27.6%, 29.3%, and 43.1%, respectively) were revealed in this study. Malassezia furfur, M. sympodialis, and M. globosa showed different susceptibility profiles to the drugs tested. These results emphasize the importance of accurately identifying and evaluating the antifungal susceptibility of Malassezia species in order to guide a specific and effective treatment regimen.

Virulence factors of Malassezia strains isolated from pityriasis versicolor patients and healthy individuals

Over the last decade, Malassezia species have emerged as increasingly important pathogens associated with a wide range of dermatological disorders and bloodstream infections. The pathogenesis of Malassezia yeasts is not completely clear but it seems to be strictly related to Malassezia strains and hosts and need to be better investigated. This study aimed to assess the enzymatic activities, biofilm formation and in vitro antifungal profiles of Malassezia spp. from Pityriasis versicolor and heathy patients. The potential relationship between virulence attributes, the antifungal profiles and the origin of strains were also assessed. A total of 44 Malassezia strains isolated from patients with (n = 31) and without (n = 13) Pityriasis versicolor (PV) were employed to evaluate phospholipase (Pz), lipase (Lz), hemolytic (Hz) activities and biofilm formation. In addition, in vitro antifungal susceptibility testing was conducted using the CLSI broth microdilution with some modifications. A high percentage of strains produced phospholipase, lipase, hemolysins and biofilm regardless of their clinical origin. The highest number of strains producing high enzymatic activities came from PV patients. A correlation between the intensity of hydrolytic activities (lipase and phospholipase activities) and the hemolytic activity was detected. Positive associations between Lz and the low fluconazole susceptibility and Hz and biofilm formation were observed. These results suggest that enzyme patterns and biofilm formation together with antifungal profiles play a role in the pathogenicity of Malassezia spp. and might explain the implication of some Malassezia spp. in invasive fungal infections and in the development of inflammation.

Microbial communities of the olive mill wastewater sludge stored in evaporation ponds: The resource for sustainable bioremediation

Olive Mill Wastewater (OMW) is a polluting residue from the olive oil industry. It is usually stored in open-air unprotected evaporation ponds where their sediments accumulate. This study compares the characteristics of OMW sludges stored for long-time in evaporation ponds and assesses their impact on the underlying soil layer. Physicochemical parameters, toxicity bioassays, and full characterization of the microbial community were analyzed. The extension of the polluting effects was assessed by analysis of toxicity, microbial biomass carbon, and respiration. Geostatistics was used to predict their spatial distribution. Organic matter and polyphenol content besides toxicity levels determine variations between OMW sludges and have a high impact on the microbiota they contain. The microbial community was abundant, diverse, and functionally active. However, the biodegradability of the sludges was hindered by the toxicity levels. Toxicity and biomass carbon were higher on the surface of the ponds than in the soil layer revealing a reduced leach flow and depletion of contaminants. The natural microbiota might be biostimulated by means of applying sustainable and feasible biological treatments in order to favor the OMW sludges bioremediation. These results open up the possibility of solving the environmental concern caused by its storage in similar scenarios, which are common in olive oil-producing countries.

Cutaneous Malassezia: Commensal, Pathogen, or Protector?

The skin microbial community is a multifunctional ecosystem aiding prevention of infections from transient pathogens, maintenance of host immune homeostasis, and skin health. A better understanding of the complex milieu of microbe-microbe and host-microbe interactions will be required to define the ecosystem's optimal function and enable rational design of microbiome targeted interventions. Malassezia, a fungal genus currently comprising 18 species and numerous functionally distinct strains, are lipid-dependent basidiomycetous yeasts and integral components of the skin microbiome. The high proportion of Malassezia in the skin microbiome makes understanding their role in healthy and diseased skin crucial to development of functional skin health knowledge and understanding of normal, healthy skin homeostasis. Over the last decade, new tools for Malassezia culture, detection, and genetic manipulation have revealed not only the ubiquity of Malassezia on skin but new pathogenic roles in seborrheic dermatitis, psoriasis, Crohn's disease, and pancreatic ductal carcinoma. Application of these tools continues to peel back the layers of Malassezia/skin interactions, including clear examples of pathogenicity, commensalism, and potential protective or beneficial activities creating mutualism. Our increased understanding of host- and microbe-specific interactions should lead to identification of key factors that maintain skin in a state of healthy mutualism or, in turn, initiate pathogenic changes. These approaches are leading toward development of new therapeutic targets and treatment options. This review discusses recent developments that have expanded our understanding of Malassezia's role in the skin microbiome, with a focus on its multiple roles in health and disease as commensal, pathogen, and protector.

A case of anti- pityriasis versicolor therapy that preserves healthy mycobiome

Background

The impact of Malassezia yeasts on skin mycobiome and health has received considerable attention recently. Pityriasis versicolor (PV), a common dermatosis caused by Malassezia genus worldwide, is a manifestation of dysbiosis. PV can be associated with hyper- and/or hypopigmented skin lesions. This disease entity is characterized by high percentage of relapses, which demands a proper antifungal therapy that is based on unambiguous species identification and drug susceptibility testing.

Case presentation

Comprehensive analysis of PV case in man presenting simultaneously hyper- and hypopigmented skin lesions was performed. Conventional and molecular diagnostic procedures revealed Malassezia furfur and Malassezia sympodialis, respectively as etiological agents of skin lesions observed. Susceptibility tests showed significantly lowered sensitivity of M. furfur cells to fluconazole. Based on susceptibility profiles local antifungal therapy with drugs characterized by entirely different mechanism of action was included.

Conclusions

Our study indicates that cases of PV represented by two types of skin lesions in one patient may be associated with distinct Malassezia species. Moreover, as observed in this case, each of the isolated etiological agents of PV may differ significantly in susceptibility to antifungals. This can significantly complicate the treatment of dermatosis, which by definition is associated with a significant percentage of relapses. In the presented case localized topical treatment was sufficient and successful while allowing maintaining the physiological mycobiome.

Comparative study between topically applied irradiated human amniotic membrane in combination with tea tree oil versus topical tioconazole in pityraisis versicolor treatment

Pityriasis versicolor (PV) is a chronic skin disease caused by virulence activities of Malassezia, a genus of skin-associated yeasts. Traditionally, Tioconazole is used as a topical antifungal for curing PV. Previous investigations cited that human amniotic membrane (HAM), a placental tissue, has antimicrobial and anti-inflammatory activities and is useful as a dressing for healing skin lesions. Moreover, tea tree oil (TTO) has a potent antifungal efficacy. This clinical trial aims to achieve an alternative therapeutic treatment able to kill Malassezia and heal PV lesions using TTO-saturated HAM (TOSHAM), with little application times. This study subjected 120 patients with hypopigmented or hyperpigmented PV lesions; half patients were treated weekly with TOSHAM compared with the others who applying 1% Tioconazole cream daily as a traditional treatment. Microbiological evaluation of in vitro fungicidal activity of TOSHAM versus Tioconazole was carried out against Malassezia furfur culture. The clinical outcomes of this study proved the superior activity of TOSHAM to heal PV lesions than Tioconazole; this was in harmony with microbiological findings. This study approached a novel therapeutic treatment of PV with great outcomes by using TOSHAM.

Fluconazole-loaded solid lipid nanoparticles topical gel for treatment of pityriasis versicolor: formulation and clinical study

Solid lipid nanoparticles (SLNs) are very potential formulations for topical delivery of antifungal drugs. Hence, the purpose of this research was to formulate the well-known antifungal agent Fluconazole (FLZ)-loaded SLNs topical gel to improve its efficiency for treatment of Pityriasis Versicolor (PV). FLZ-SLNs were prepared by modified high shear homogenization and ultrasonication method using different concentration of solid lipid (Compritol 888 ATO, Precirol ATO5) and surfactant (Cremophor RH40, Poloxamer 407). The physicochemical properties and the in vitro release study for all FLZ-SLNs were investigated. Furthermore, the optimized FLZ-SLN formula was incorporated into gel using Carpobol 934. A randomized controlled clinical trial (RCT) of potential batches was carried out on 30 well diagnosed PV patients comparing to market product Candistan® 1% cream. Follow up was done for 4 weeks by clinical and KOH examinations. The results showed that FlZ-SLNs were almost spherical shape having colloidal sizes with no aggregation. The drug entrapment efficiency ranged from 55.49% to 83.04%. The zeta potential values lie between -21 and -33 mV presenting good stability. FLZ showed prolonged in vitro release from SLNs dispersion and its Carbapol gel following Higuchi order equation. Clinical studies registered significant improvement (p < .05) in therapeutic response (1.4-fold; healing%, 4-fold; complete eradication) in terms of clinical cure and mycological cure rate from PV against marketed cream. Findings of the study suggest that the developed FLZ loaded SLNs topical gels have superior significant fast therapeutic index in treatment of PV over commercially available Candistan® cream.

Acquired disorders with hypopigmentation: A clinical approach to diagnosis and treatment

Acquired hypopigmented skin changes are commonly encountered by dermatologists. Although hypopigmentation is often asymptomatic and benign, occasional serious and disabling conditions present with cutaneous hypopigmentation. A thorough history and physical examination, centered on disease distribution and morphologic findings, can aid in delineating the causes of acquired hypopigmented disorders. The second article in this 2-part continuing medical education series focuses on conditions with a hypopigmented phenotype. Early diagnosis and appropriate management of these disorders can improve a patient's quality of life, halt disease progression, and prevent irreversible disability.

Ketoconazole inhibits Malassezia furfur morphogenesis in vitro under filamentation optimized conditions

Malassezia furfur, a constituent of the normal human skin flora, is an etiological agent of pityriasis versicolor, which represents one of the most common human skin diseases. Under certain conditions, both exogenous and endogenous, the fungus can transition from a yeast form to a pathogenic mycelial form. To develop a standardized medium for reproducible production of the mycelial form of M. furfur to develop and optimize susceptibility testing for this pathogen, we examined and characterized variables, including kojic acid and glycine concentration, agar percentage, and pH, to generate a chemically defined minimal medium on which specific inoculums of M. furfur generated the most robust filamentation. Next, we examined the capacity of ketoconazole to inhibit the formation of M. furfur mycelial form. Both low and high, 0.01, 0.05 and 0.1 µg/ml concentrations of ketoconazole significantly inhibited filamentation at 11.9, 54.5 and 86.7%, respectively. Although ketoconazole can have a direct antifungal effect on both M. furfur yeast and mycelial cells, ketoconazole also has a dramatic impact on suppressing morphogenesis. Since mycelia typified the pathogenic form of Malassezia infection, the capacity of ketoconazole to block morphogenesis may represent an additional important effect of the antifungal.

Domestic shower hose biofilms contain fungal species capable of causing opportunistic infection

The domestic environment can be a source of pathogenic bacteria. We show here that domestic shower hoses may harbour potentially pathogenic bacteria and fungi. Well-developed biofilms were physically removed from the internal surface of shower hoses collected in four locations in England and Scotland. Amplicon pyrosequencing of 16S and 18S rRNA targets revealed the presence of common aquatic and environmental bacteria, including members of the Actinobacteria, Alphaproteobacteria, Bacteroidetes and non-tuberculous Mycobacteria. These bacteria are associated with infections in immunocompromised hosts and are widely reported in shower systems and as causes of water-acquired infection. More importantly, this study represents the first detailed analysis of fungal populations in shower systems and revealed the presence of sequences related to Exophiala mesophila, Fusarium fujikuroi and Malassezia restricta. These organisms can be associated with the environment and healthy skin, but also with infection in compromised and immuno-competent hosts and occurrence of dandruff. Domestic showering may result in exposure to aerosols of bacteria and fungi that are potentially pathogenic and toxigenic. It may be prudent to limit development of these biofilms by the use of disinfectants, or regular replacement of hoses, where immuno-compromised persons are present.

Antifungal Treatment for Pityriasis Versicolor

BACKGROUND

Pityriasis versicolor (PV), also known as tinea versicolor, is caused by Malassezia species. This condition is one of the most common superficial fungal infections worldwide, particularly in tropical climates. PV is difficult to cure and the chances for relapse or recurrent infections are high due to the presence of Malassezia in the normal skin flora. This review focuses on the clinical evidence supporting the efficacy of antifungal treatment for PV.

METHOD

A systematic review of literature from the PubMed database was conducted up to 30 September 2014. The search criteria were "(pityriasis versicolor OR tinea versicolor) AND treatment", with full text available and English language required.

CONCLUSIONS

Topical antifungal medications are the first-line treatment for PV, including zinc pyrithione, ketoconazole, and terbinafine. In cases of severe or recalcitrant PV, the oral antifungal medications itraconazole and fluconazole may be more appropriate, with pramiconazole a possible future option. Oral terbinafine is not effective in treating PV and oral ketoconazole should no longer be prescribed. Maintenance, or prophylactic, therapy may be useful in preventing recurrent infection; however, at this time, there is limited research evaluating the efficacy of prophylactic antifungal treatment.

[Recent advances in research on Malassezia microbiota in humans]

Malassezia species of lipophilic yeasts account for most fungal microbiota. Although they colonize healthy skin, they are also associated with several skin diseases, including pityriasis versicolor, seborrheic dermatitis, Malassezia folliculitis, and atopic dermatitis. To date, 14 members of the Malassezia genus have been identified. Of these, both M. globosa and M. restricta predominate, regardless of skin-disease type. Comprehensive analysis of fungal microbiota in the skin of patients with atopic dermatitis using an rRNA clone library method revealed that fungal microbiota cluster according to disease severity. The external ear canal and sole of the foot are colonized by specific Malassezia microbiota.

Distribution of Malassezia species on the skin of patients with atopic dermatitis, psoriasis, and healthy volunteers assessed by conventional and molecular identification methods

Background

The Malassezia yeasts which belong to the physiological microflora of human skin have also been implicated in several dermatological disorders, including pityriasis versicolor (PV), atopic dermatitis (AD), and psoriasis (PS). The Malassezia genus has repeatedly been revised and it now accommodates 14 species, all but one being lipid-dependent species. The traditional, phenotype-based identification schemes of Malassezia species are fraught with interpretative ambiguities and inconsistencies, and are thus increasingly being supplemented or replaced by DNA typing methods. The aim of this study was to explore the species composition of Malassezia microflora on the skin of healthy volunteers and patients with AD and PS.

Methods

Species characterization was performed by conventional, culture-based methods and subsequently molecular techniques: PCR-RFLP and sequencing of the internal transcribed spacer (ITS) 1/2 regions and the D1/D2 domains of the 26S rRNA gene. The Chi-square test and Fisher’s exact test were used for statistical analysis.

Results

Malassezia sympodialis was the predominant species, having been cultured from 29 (82.9%) skin samples collected from 17 out of 18 subjects under the study. Whereas AD patients yielded exclusively M. sympodialis isolates, M. furfur isolates were observed only in PS patients. The isolation of M. sympodialis was statistically more frequent among AD patients and healthy volunteers than among PS patients (P < 0.03). Whether this mirrors any predilection of particular Malassezia species for certain clinical conditions needs to be further evaluated. The overall concordance between phenotypic and molecular methods was quite high (65%), with the discordant results being rather due to the presence of multiple species in a single culture (co-colonization) than true misidentification. All Malassezia isolates were susceptible to cyclopiroxolamine and azole drugs, with M. furfur isolates being somewhat more drug tolerant than other Malassezia species.

Conclusions

This study provides an important insight into the species composition of Malassezia microbiota in human skin. The predominance of M. sympodialis in both normal and pathologic skin, contrasts with other European countries, reporting M. globosa and M. restricta as the most frequently isolated Malassezia species.

The role of L-DOPA on melanization and mycelial production in Malassezia furfur

Melanins are synthesized by organisms of all biological kingdoms and comprise a heterogeneous class of natural pigments. Certain of these polymers have been implicated in the pathogenesis of several important human fungal pathogens. This study investigated whether the fungal skin pathogen Malassezia furfur produces melanin or melanin-like compounds. A melanin-binding monoclonal antibody (MAb) labelled in vitro cultivated yeast cells of M. furfur. In addition, melanization of Malassezia yeasts and hyphae was detected by anti-melanin MAb in scrapings from patients with pityriasis versicolor. Treatment of Malassezia yeasts with proteolytic enzymes, denaturant and concentrated hot acid yielded dark particles and electron spin resonance spectroscopy revealed that these particles contained a stable free radical compound, consistent with their identification as melanins. Malassezia yeasts required phenolic compounds, such as L-DOPA, in order to synthesize melanin. L-DOPA also triggered hyphal formation in vitro when combined with kojic acid, a tyrosinase inhibitor, in a dose-dependent manner. In this respect, L-DOPA is thought to be an essential substance that is linked to both melanization and yeast-mycelial transformation in M. furfur. In summary, M. furfur can produce melanin or melanin-like compounds in vitro and in vivo, and the DOPA melanin pathway is involved in cell wall melanization.

A 7-year survey of superficial and cutaneous mycoses in a public hospital in Natal, Northeast Brazil

In the present study, we determined the frequency of superficial and cutaneous mycoses and their etiologic agents during a 7-year period (2002–2008) in Natal, Brazil. A total of 1,717 specimens of skin, nail, and hair were collected from 1,382 patients with suspected mycoses lesions and were then subjected to direct microscopy and culture.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Glycine as a regulator of tryptophan-dependent pigment synthesis in Malassezia furfur

The effects of the addition of different amino nitrogens on growth, morphology and secondary metabolism of Malassezia furfur were investigated. After primary culture on Dixon agar, M. furfur CBS 1878 was transferred into a fluid medium together with the nitrogen sources, glycine (Gly) or tryptophan (Trp), or a combination of both. Growth was measured by means of a direct cell counting method and pigment synthesis was photometrically assessed. Addition of glycine resulted in an exponential increase in biomass, but not in pigment production. Tryptophan as the sole nitrogen source caused distinct brown staining of the medium, without increasing biomass. Simultaneous equimolar addition of both amino acids resulted in an initial increase in biomass as a sign of preferential metabolism of glycine, followed by a growth plateau and pigment production which, caused by higher biomass, occurred more rapidly than after addition of tryptophan alone. The yeast-cell morphology changed from round to oval. Addition of glycine to the tryptophan-containing liquid culture stopped pigment formation with simultaneous growth induction. These in vitro on-off phenomena depending on the nitrogen source might be significant in the pathogenesis of pityriasis versicolor: hyperhidrosis followed by preferential consumption of individual nitrogen sources such as glycine with exponential growth and thereafter transamination of tryptophan and TRP-dependent pigment synthesis.

Cutaneous malasseziasis: four case reports of atypical dermatitis and onychomycosis caused by Malassezia

BACKGROUND

This study investigates four special cases associated with Malassezia.

METHODS

The special clinical manifestations, mycologic examination, and treatment were reviewed intensively.

RESULTS

An abundance of Malassezia hyphae were found in the scales of the three cases presenting with erythematous patches and in another case presenting with dystrophic nails. Malassezia globosa was identified and confirmed by culture. Antifungal agents were effective in the treatment of all cases.

CONCLUSIONS

Malassezia is an opportunistic fungus that may induce dermatosis other than classical pityriasis versicolor. Hyphae from the lesions may be induced by a change in the microenvironment of the fungus caused by the local application of corticosteroids.

Tinea versicolor, tinea nigra, white piedra, and black piedra

Superficial mycoses are fungal infections limited to the stratum corneum and its adnexal structures. The most frequent types are dermatophytoses or tineas. Tinea versicolor involves the skin in the form of hypochromic or hyperchromic plaques, and tinea nigra affects the skin of the palms with dark plaques. White piedra and black piedra are parasitic infections of scalp hairs in the form of concretions caused by fungal growth. Diagnosis of these mycoses is made from mycologic studies, direct examination, stains, and isolation, and identification of the fungi. Treatment includes systemic antifungals, topical antifungals, and keratolytics.

Bilateral areolar and periareolar pityriasis versicolor

An adolescent boy presented with isolated, symmetrical, bilateral areolar and periareolar pityriasis versicolor. This extremely rare condition should be considered in the differential diagnosis of light brown patches on the areolae.

Pigmentary disorders

A large number of pigmentary disorders exist and although not all dermatologic entities are covered in this article, some of the pigmentary disorders that an internist or general practitioner is likely to encounter are reviewed. The clinician must be able to recognize pigmentary changes that suggest a serious underlying disease. In a situation where a malignancy or other serious illness may exist, an extensive evaluation to detect the disorder is required. This approach can allow for early treatment and referral to an appropriate specialist if necessary. The clinician must also recognize that pigmentary disorders that are essentially cosmetic still cause concern for the patient and can be emotionally distressing. These patients need emotional support and in some cases referral to a mental health specialist.

Physiological and molecular characterization of atypical isolates of Malassezia furfur

The species constituting the genus Malassezia are considered to be emergent opportunistic yeasts of great importance. Characterized as lipophilic yeasts, they are found in normal human skin flora and sometimes are associated with different dermatological pathologies. We have isolated seven Malassezia species strains that have a different Tween assimilation pattern from the one typically used to differentiate M. furfur, M. sympodialis, and M. slooffiae from other Malassezia species. In order to characterize these isolates of Malassezia spp., we studied their physiological features and conducted morphological and molecular characterization by PCR-restriction fragment length polymorphism and sequencing of the 26S and 5.8S ribosomal DNA-internal transcribed spacer 2 regions in three strains from healthy individuals, four clinical strains, and eight reference strains. The sequence analysis of the ribosomal region was based on the Blastn algorithm and revealed that the sequences of our isolates were homologous to M. furfur sequences. To support these findings, we carried out phylogenetic analyses to establish the relationship of the isolates to M. furfur and other reported species. All of our results confirm that all seven strains are M. furfur; the atypical assimilation of Tween 80 was found to be a new physiological pattern characteristic of some strains isolated in Colombia.

Molecular analysis of Malassezia species isolated from hospitalized neonates

Malassezia species are a part of the skin microflora of neonates. Under certain circumstances, they can cause diseases ranging from simple pustulosis to lifethreatening fungemia in newborn infants. Little information is available about the epidemiology of Malassezia species in neonates. In the present study, we successfully isolated Malassezia yeasts from 68.7% of hospitalized neonates. Using the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFPL), M. furfur (88.06%) was identified as the most isolated species, followed in frequency by M. globosa (10.48%), M. obtusa (0.73%), and M. slooffiae (0.73%). Among the variables studied, only a longer stay in the ward resulted in a higher colonization rate. Using multiple logistic regression, only the type of hospital and ward had some effects on the colonization rate. Our results supported the hypothesis that neonates acquire Malassezia flora through direct contact with their mothers or hospital personnel.

The genetic epidemiology of tinea versicolor in China

To study the clinical and epidemiological profile of Pityriasis versicolor (PV) and to determine the possible genetic model for PV in Chinese Han, we investigated 503 patients with PV who were recruited by a questionnaire method. Statistical analysis, heritability and complex segregation analysis were performed using EPI INFO 6.0, SPSS 10.0, the Falconer method and the SAGE-REGTL programs. In the total 503 PV patients, the mean age of onset was 22.85 +/- 10.36 years. For male and female patients, the peak ages of initial onset were both 20-29 years. A total of 106 (21.1%) patients were reported to have a positive family history of PV. The mean age of onset in males with positive family history was earlier than those with negative family history (t = 3.58, P < 0.01). Higher rate of recurrence and longer duration were seen in the patients with positive family history than those with negative family history. The heritability of PV in first-, second- and third-degree relatives was 48.13%, 40.11% and 27.20% respectively. Based on the REGTL results, the best model was a polygenic additive model for PV.

Origin, clinical presentation, and diagnosis of hypomelanotic skin disorders

Hypomelanotic skin disorders are cutaneous pigmentary disorders characterized by a reduced melanin content in the skin that results in a lightening of the skin. Establishing the correct diagnosis for hypomelanotic skin disorders requires a good history, a detailed physical examination, the use of special lighting techniques, such as Wood's light, and sometimes a biopsy of the abnormally pigmented skin and the normally pigmented skin. This article focuses on the origin, clinical presentation, and diagnosis of acquired hypomelanotic skin disorders. An algorithm for the diagnostic approach to these hypomelanoses is given.

Skin disease is common in rural Nepal: results of a point prevalence study

BACKGROUND

Skin problems are the commonest reason for people accessing healthcare services in Nepal but there is little information about the prevalence of skin disease.

OBJECTIVES

To perform a point prevalence study of skin disease in the Terai region of Nepal.

METHODS

Five villages were randomly selected in Bara District in the Terai region of Nepal, and 878 people were examined.

RESULTS

The number of individuals identified as having a skin disease was 546. The point prevalence of identifiable skin abnormalities was 62.2% (546 of 878) (with 95% exact confidence intervals 58.9-65.4%). A wide range of dermatoses was identified. The six most prevalent were dermatophyte infections (11.4%), followed by pityriasis versicolor (8.9%), acne (7.7%), melasma (6.8%), eczema (5.6%) and pityriasis alba (5.2%). Overall, treatable skin infections and infestations were by far the commonest skin diseases identified.

CONCLUSIONS

Our study has demonstrated a very high point prevalence (62.2%) of skin disease in rural Nepal. This study represents the first formal survey of skin disease in Nepal and demonstrates a large burden of disease, in particular treatable infections.

Genotyping by RAPD-PCR analyses of Malassezia furfur strains from pityriasis versicolor and seborrhoeic dermatitis patients

Malassezia furfur is lypophilic yeast commonly associate with dermatological disorders. In the present work, we described the isolation of 47 M. furfur strains from three groups of patients: pityriasis versicolor (21 isolates), seborrhoeic dermatitis (15 isolates) and seborrhoeic dermatitis of the HIV positive patients (11 isolates). To investigate the identity of the strains at molecular level, DNA genomic of M. furfur strains were prepared and used to RAPD-PCR analyses. RAPD assay were carried out using two decamer primers and bands pattern generated were analyzed by an Unweighted Pair-Group Method (UPGMA). Dendrogram established a distinct differentiation between M. furfur isolates from pityriasis versicolor and seborrhoeic dermatitis patients with or without AIDS. We concluded that RAPD typing presented a high discriminatory power between strains studied in this work and can be applied in epidemiological investigation of skin disease causing by M. furfur.

Microcoding and flow cytometry as a high-throughput fungal identification system for Malassezia species

Yeasts of the genus Malassezia have been associated with a variety of dermatological disorders in humans and domestic animals. With the recent recognition of new members of the genus, new questions are emerging with regard to the pathogenesis and epidemiology of the new species. As new species are recognized, a precise and comprehensive identification system is needed. Herein is described a bead suspension culture-based array that combines the specificity and reliability of nucleic acid hybridization analysis with the speed and sensitivity of the Luminex analyser. The developed 16-plex array consisted of species- and group-specific capture probes that acted as 'microcodes' for species identification. The probes, which were designed from sequence analysis in the D1/D2 region of rRNA and internal transcribed spacer (ITS) regions, were covalently bound to unique sets of fluorescent beads. Upon hybridization, the biotinylated amplicon was detected by the addition of a fluorochrome coupled to a reporter molecule. The hybridized beads were subsequently analysed by flow cytometric techniques. The developed array, which allowed the detection of species in a multiplex and high-throughput format, was accurate and fast, since it allowed precise identification of species and required less than 1 h following PCR amplification. The described protocol, which can integrate uniplex or multiplex PCR reactions, permitted the simultaneous detection of target sequences in a single reaction, and allowed single mismatch discrimination between probe and non-target sequences. The assay has the capability to be expanded to include other medically important pathogenic species in a single or multiplex array format.