Isolation of Malassezia Species from Clinically Diagnosed Cases of Pityriasis Versicolor and Seborrheic Dermatitis and Determination of Antifungal Susceptibility of the Isolates

INTRODUCTION: Ever since its inception, the genus Malassezia has been a topic of intense basic research in various aspects including taxonomy, physiology, epidemiology, metabolomics and immunology. The etiopathologic links between these yeasts and many superficial and systemic infections have been unveiled by clinical research. Pityriaisvericolor (PV) and seborrheic dermatitis (SD) are superficial skin infections that have an established causal association with Malassezia species. OBJECTIVES: The objective of this study is to make use of the biochemical and physiologic differences among the various species of Malassezia to gain an insight into the epidemiology and the risk factor associations of these yeasts with pityriasisversicolor and seborrheic dermatitis in this part of our country, known for its hot and humid climate, which favours the growth of these yeasts and also to determine the antifungal susceptibility of the isolates to the commonly used azoles and amphotericin B. MATERIALS AND METHODS: This study was done at Madras Medical College, Chennai for a period of one year involving 100 clinically diagnosed cases of Malassezia infections, of whom 73 had pityriasisversicolor and 27 had seborrheic dermatitis. Skin scrapings from the lesional sites were collected using strict aseptic precautions and processed bystandard microbiological methods. Christensen’s urease medium with the addition of Tween compounds was used for antifungal susceptibility testing of the Malassezia isolates to fluconazole, itraconazole, ketoconazole, voriconazole and amphotericin B. RESULTS: Pityriasisversicolor commonly occurred in the 20 – 29 years age group (42.5%) and seborrheic dermatitis in the 40 -49 years age group (44.5%). Males were affected more commonly than females with both PV (72.6% males) and SD (74% males). Majority of the PV patients presented with lesions on the back (50.7%). Face and scalp (63%) were the common sites involved in SD. Majority of PV patients had hypopigmented lesions (63.1%). The overall culture positivity rate was 70%, the yield being higher with PV lesions. Among the PV cases, 92.6% of the hyperpigmented lesions were culture positive. M. globosa was the most common species isolated in PV and SD. Low MIC ranges and low MIC50 values of < 1 μg/ml were noted with amphotericin B, ketoconazole and itraconazole for most of the Malassezia species. CONCLUSION: Culture is an important step in the diagnosis of Malasseziainfections due to interspecies variability exhibited by Malassezia species in the etiological role in different geographical areas and differences in their susceptibility patterns to antifungal agents. Culture and antifungal susceptibility testing in the management of Malassezia infections will lead to a better targeted approach, reducing the cosmetic concerns, chronicity and recurrences associated with these infections

Seborrheic dermatitis and its relationship with Malassezia spp

La dermatitis seborreica (DS) es una enfermedad inflamatoria crónica, con un elevado impacto en la calidad de vida del individuo. Además, DS es una entidad multifactorial que ocurre como respuesta inflamatoria a las levaduras del género Malassezia spp., junto con factores desencadenantes que contribuyen a la fisio¬patología de la enfermedad. Dado que el mecanismo patogénico principal involucra la proliferación e inflamación generada por Malassezia spp., el tratamiento más usado son los agentes tópicos antifúngicos y antiinflamatorios. Sin embargo, se desconocen las consecuencias de eliminar la población de levaduras de la piel, los perfiles de resistencia de Malassezia spp. y la efectividad entre grupos diferentes de medicamentos. Por tanto, en esta revisión de la literatura, resumimos el conocimiento actual sobre la fisiopatología de la enfermedad y el papel de Malassezia sp., así como de las diferentes alternativas de tratamiento antifúngico tanto tópico como oral en el manejo de la DS.Seborrheic dermatitis (SD) is a chronic inflammatory disease that that is difficult to manage and with a high impact on the individual’s quality of life. Besides, it is a multifactorial entity that typically occurs as an inflammatory response to Malassezia species, along with specific triggers that contribute to its pathophysiology. Sin¬ce the primary underlying pathogenic mechanisms include Malassezia proliferation and skin inflammation, the most common treatment includes topical antifungal keratolytics and anti-inflammatory agents. However, the consequences of eliminating the yeast population from the skin, the resistance profiles of Malassezia spp. and the effectivity among different groups of medications are unknown. Thus, in this review, we summarize the current knowledge on the disease´s pathophysio¬logy and the role of Malassezia sp. on it, as well as, the different antifungal treatment alternatives, including topical and oral treatment in the management of SD

Clinico epidemiological and mycological study of pityriasis versicolor

Pityriasis versicolor, a mild, chronic superficial, cutaneous mycosis caused by Malassezia species is characterised by discrete or confluent, scaly, discoloured areas mainly on the upper trunk and other seborrheic areas. This infection commonly occurs in adolescents and young adults. AIMS AND OBJECTIVES : 1. To study the epidemiology of pityriasis versicolor. 2. To study the various clinical types. 3. To study the association of pityriasis versicolor with other dermatological disorders and systemic diseases 4. To identify the various species of Malassezia 5. To study the clinicomycological correlation. MATERIALS AND METHODS : 100 patients with pityriasis versicolor were randomly selected. Detailed history was taken and clinical examination was done. Scraping was done for all the patients KOH positive scrapings were subjected to culture in SDA with olive oil overlay. Tween assimilation was done from positive cultures and species isolation done. Gram staining was done from positive cultures. OBSEVATION AND RESULTS : Pityriasis versicolor is most commonly seen in the age group between 21- 30years.Males outnumbered the females. PV was more common among the students.Urban population was affected more than the rural population. Cosmetic concern was the main complaint. Duration of lesion in majority of the patients was 1 to 6 months. Diabetes and Seborrheic dermatitis was found to be the most commonly associated. Blood group A was commonly affected. Most common site was back and majority of the patients had more than 30%BSA.Achromicpityriasis versicolor was more common.Malasseziaglobosa was the most common species isolated. CONCLUSION : There is no significant change in clinico-epidemiology and presentation of pityriasis versicolor.A blood group was the most common blood group associated with pityriasis versicolor which is different from the previous study in which O blood group is the commonest association. Hence, further studies in a larger population would provide more conclusive evidence with regard to the blood groups

Identification of Malassezia Species in Pityriasis Versicolor.

INTRODUCTION : The skin is the body’s largest and thinnest organ. Approximately, 15 percent of all patients who seek medical attention have either some skin disease or skin lesion, many of which are infectious. Fungi are ubiquitous in the environment. Fungal infections of the skin are a health concern worldwide. Clinical fungal infections are generally divided into four types namely, cutaneous, subcutaneous systemic and opportunistic mycosis. Superficial mycosis are by far the most common. Superficial fungal infections are defined as infections in which a pathogen is restricted to the stratum corneum, with little or no tissue reaction. One of the superficial fungal infections of the skin is Pityriasis versicolor. Tinea versicolor, also known as Pityriasis versicolor, is one of the most common pigmentary disorders worldwide. In the United States, the name Tinea versicolor is commonly used, whereas Pityriasis versicolor is the common name in Europe. Perhaps, European colleagues are correct, since the name “Tinea” suggests that the infection is caused by a dermatophyte, which, of course, is untrue. In view of the wide spectrum of diseases caused by Malassezia spp. it was, therefore, felt necessary to study the most common Malassezia spp. associated with patients having Pityriasis versicolor and analyse the risk factors leading to the infection. AIMS AND OBJECTIVES : 1. To identify the yeasts isolated from clinically diagnosed patients with Pityriasis versicolor. 2. To evaluate Modified Dixon’s Agar for isolation of the Malassezia species. 3. To compare Modified Dixon’s Agar and Sabouraud Dextrose Agar with Olive oil overlay for isolation of Malassezia spp. 4. To speciate the Malassezia isolates using Tween Assimilation Tests. 5. To analyse the risk factors which promote Malassezia fungus infection. MATERIALS AND METHODS : This cross sectional study was done in the Institute of Microbiology, Madras Medical College and the Mycology section of the Department of Dermatology, Government General Hospital, Chennai from July 2005 to June 2006. The study group included both male and female outpatients of all age groups, attending the mycology section of the Department of Dermatology, with complaints of hypopigmented or hyperpigmented macular lesions. The skin scrapings were collected from 112 clinically diagnosed patients with Pityriasis versicolor. RESULTS : Pityriasis versicolor accounted for 16.6 percent patients with dermatomycoses in Government General Hospital, Chennai. Majority of the study population belonged to the age range 21-30 years. Male patients out numbered female patients. Maximum number of cases occurred during July to August. Majority of patients had hypopigmented lesions. Majority of patients presented within 2 months of onset of the lesion. Chest and back regions were the most commonly affected sites. Lower limb, hip palms, soles, and gluteal regions were not involved. Both mounts found to be equally sensitive. Out of 104 Pityriasis versicolor patients, only 66(63.46%) were culture positive for Malassezia yeast. Modified Dixon’s Agar had 7.69% higher isolation rates than SDA with Olive oil overlay. Modified Dixon’s Agar had 7.69% higher isolation rates than SDA with Olive oil overlay. M. globosa was the predominant species isolated in Pityriasis versicolor cases. Increased sweating was identified to be the predominant risk factor. Increased sweating was found to be the statistically significant risk for Pityriasis versicolor with P value of 0.0001. No conjugal relationship was not seen in this study

The skin immune response to Malassezia furfur

The paradoxical nature of M furfur colonisation versus infection in dermatological disease is subject to much research. The aim of this experimental work was to measure the innate immune response of the skin to M. furfur, via the use of skin models. Living skin equivalents (LSE), excised breast reduction tissue (BRT) and keratinocyte (KC) monolayers were all utilised in an attempt to elucidate the possible immune evasive and stimulatory capabilities of M. furfur. The constitutive production of human p defensin 2 (HBD-2), an inducible antimicrobial peptide, was measured KC monolayers, LSEs and BRT. In addition the skin model's response to fungal challenge was elucidated. Wide variation in the basal expression of HBD-2 was detected in all skin model donors. M. furfur cell wall and killed whole M. furfur initiated a slight depression in HBD-2 expression by KC monolayers, however these results were not statistically significant in all donors and merely indicated a trend. Likewise KC monolayers, BRT and LSEs reacted to viable M. furfur with slight inhibition of HBD-2 production at 24hr with subsequent stimulation of expression. However donor variation in this pattern was detected and these results were not continuously significant. Due to the non-continuous nature of these measurements these results were inconclusive. As M furfur infection of the skin is associated with alteration of the normal pigmentation in patients, melanin synthesis by B16 mouse melanoma cells and BRT was assessed in response to M. furfur. Viable M. jurjur and C. albicans stimulated an increase in melanin synthesis in B16 mouse melanoma cells. The ability of viable M. furfur cells to stimulate melanin synthesis appeared to be localised within the cytoplasm of the organism. However, this 'viable cell stimulation' did not appear to be restricted to M. furfur, as C. albicans also stimulated melanin synthesis. On BRT there was little difference in the melanin and tyrosinase production of BRT in reponse to M. furfur and C. albicans growth. The capacity of M. furfur and C. albicans cell wall to alter the cytokine profile of KCs was also measured and KC monolayers exhibited a time-dependent increase in IL-la, IL-8 and ET-1 expression in response to M. furfur and C. albicans cell wall. C. albicans cell wall initiated a significantly greater increase in the expression of these cytokines by the KCs. However little correlation between the mRNA production and peptide production was measured using RT-PCR. Growth of M furfur and C. albicans on the skin models was assessed using scanning electron microscopy (SEM) and histological observation of the colonized tissue. Growth was also compared by means of viable cell counts. The effect of growth on the proliferation of the epidermis was measured by counting the number of proliferating cells in the basal layer of the epidermis of each tissue. Growth of M. furfur and C. albicans was detected on LSE and BRT and hyphal transformation of both organisms was observed on BRT and LSE, although hyphal transformation of C. albicans was found more commonly on the LSE. Indeed, overall growth of C. albicans was more widespread and rapid on LSE than it was on BRT. By contrast M. furfur appeared to undergo hyphal transformation more frequently on BRT, and this feature was donor-dependent. The viability of M. furfur varied when tested on BRT from different donors or on different batches of LSE. The proliferative index of the tissues indicated that growth of both M. furfur and C. albicans initiated an increase in the proliferation of the BRT and LSE epidermis. Overall, these studies show that growth of M. furfur and C. albicans differs in the various skin models and this effect was dependent on the different qualities of the donor tissue and donor KCs. The growth of M. furfur, while slower than that of C. albicans, does stimulate a larger increase in the proliferation of the BRT epidermis

Advances in Antifungal Development: Discovery of New Drugs and Drug Repurposing

This reprint describes recent advances made in the field of antifungal development, especially the discovery of new drugs and drug repurposing. The articles presented in this book provide useful information and insight for the development of new antifungal drugs or intervention strategies. The identification of new, safe molecules, and cellular targets, as well as the elucidation of their antifungal mechanisms of action, will further the effective control of fungal pathogens, especially those resistant to current therapeutic agents

In vitro models for assessing the pathogenicity of Malassezia yeasts

The basidiomycetous yeast Malassezia has been linked to a number of disease states such as seborrhoeic dermatitis, dandruff and pityriasis versicolor. Much confusion has arisen as to its role in these disease states as this fungus is found inhabiting the stratum corneum of approximately 90% of the human adult population. Malassezia yeasts are lipophilic organisms, some species showing a specific requirement for long chain fatty acids for in vitro culture. The object of the experiments undertaken in this study was to elucidate the role of Malassezia yeasts in dandruff and seborrhoeic dermatitis