An epidemic outbreak of Malassezia folliculitis in three adult patients in an intensive care unit: a previously unrecognized nosocomial infection

Evaluation of an in-house pan-Malassezia quantitative PCR in human clinical samples

Althought Malassezia spp. have been involved in various pathologies, they are an integral part of the cutaneous, gut, oral, ears, nose and throat (ENT) mycobiota. Since Malassezia are difficult to grow in culture, unexhaustive molecular biology methods have been developed to detect them. The aim of the study was to evaluate an in-house pan-Malassezia quantitative polymerase chain reaction (panM-qPCR) on various clinical human samples and determine Malassezia burden in various human mycobiota. The panM-qPCR was designed to target the repeated 28S rDNA gene from all Malassezia species. We used the assay to quantify the Malassezia burden on 361 samples from 161 subjects (80 skin swabs from 10 healthy volunteers (HV), 13 samples from 2 seborrheic dermatitis patients (SD), 90 skin samples from 19 burned patients, 119 stool samples from 89 immunocompromised patients, 59 ENT samples from 41 patients). For HV, the amount of Malassezia was different according to the swabbed areas. Quantification cycle (Cq) in SD is lower than in HV. In burned patients, Cq was significantly lower compared to HV. In stool samples, 6.7% were positive for Malassezia spp. with a high Cq. For the ENT area, a higher proportion of positive specimens were detected in ear samples than in nose samples. Our findings emphasized the importance of qPCR, confirming elevated Malassezia spp. levels on individuals' faces and scalps, increased burden in SD patients and in severely burnt patients than in HV. The pan-MqPCR appears to be a promising tool for studying Malassezia in various human mycobiota.

Rare Yeasts in Latin America: Uncommon Yet Meaningful

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals

Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.

Azole resistance mechanisms in pathogenic M. furfur

Malassezia are emerging fungal pathogens causing opportunistic skin and severe systemic infection. Nosocomial outbreaks are associated with azole resistance and understanding of the underlying mechanisms are limited to knowledge from other fungal species. Herein, we identified distinct antifungal susceptibility patterns in 26 Malassezia furfur isolates derived from healthy and diseased individuals. A Y67F CYP51 mutation was identified in five isolates of M. furfur However, this mutation alone was insufficient to induce reduce azole susceptibility in the wild type strain. RNA-seq and differential gene analysis of healthy and disease derived strains exposed to clotrimazole in vitro identified several key metabolic pathways and transporter proteins which are involved in reduce azole susceptibility. The pleiotropic drug transporter PDR10 was the single most highly upregulated transporter gene in multiple strains of M. furfur after azole treatment and increased expression of PDR10 is associated with reduced azole susceptibility in some systemic disease isolates of M. furfur Deletion of PDR10 in a pathogenic M. furfur strain with reduced susceptibility reduced MIC values to the level of that in susceptible isolates. The current dearth of antifungal technologies, globally emerging multi-azole resistance, and broad agriculture and consumer care use of azoles means improved understanding of the mechanisms underlying intrinsic and acquired azole resistance in Malassezia is crucial for development of antibiotic stewardship and antifungal treatment strategies.

Malassezia species in students from universities of Sabzevar, Northeastern Iran

BACKGROUND

Malassezia species, usually part of normal human skin microbiota, may also cause cutaneous infections, mainly pityriasis versicolor (PV) which may rapidly spread in crowded communities, particularly in students' dormitories and sport leisure centers.

OBJECTIVE

Few studies have been conducted on PV in students in the Middle East. The present study was designed to determine prevalence of Malassezia species and related diseases in students from city of Sabzevar, Northeast Iran.

METHODS

Specimens were collected from 189 students and analyzed by direct microscopy and cultures. Following PCR amplification of the large subunit of ribosomal DNA, species were identified by restriction fragment length polymorphism analysis (RFL-PCR).

RESULTS

PV was suspected for 28 students which was confirmed by direct examination and cultures. Cultures also revealed positive for 13 students with healthy skin. Four Malassezia species were identified, with M. restricta as the most prevalent. A higher rate of PV was observed compared to other regions in Iran. However, despite the lipophilic feature of Malassezia species, no significant association was observed between PV or Malassezia species and fatty skin or gender.

CONCLUSION

This study determined the frequencies of Malassezia species in part of Northeast Iran, but further studies are needed to identify risk factors for PV.

Malassezia-Can it be Ignored?

Genus Malassezia comprises of 14 species of “yeast like fungi,” 13 of which are lipophilic and 1 is nonlipophilic. They are known commensals and in predisposed individuals they commonly cause a spectrum of chronic recurrent infections. They rarely also cause serious illnesses like catheter-related blood stream infections, CAPD associated peritonitis etc., Though these fungi have been known to man for over 150 years, their fastidious nature and cumbersome culture and speciation techniques have restricted research. Since the last taxonomic revision, seven new species have been added to this genus. Their ability to evade the host immune system and virulence has increased the spectrum of the diseases caused by them. These agents have been implicated as causal agents in common diseases like atopic dermatitis recently. Though culture-based research is difficult, the new molecular analysis techniques and facilities have increased research in this field such that we can devote more attention to this genus to study in detail, their characteristics and their growing implications implications in the clinical scenario.

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.

Skin diseases associated with Malassezia yeasts: facts and controversies

The implication of the yeast genus Malassezia in skin diseases has been characterized by controversy, since the first description of the fungal nature of pityriasis versicolor in 1846 by Eichstedt. This is underscored by the existence of Malassezia yeasts as commensal but also by their implication in diseases with distinct absence of inflammation despite the heavy fungal load (pityriasis versicolor) or with characteristic inflammation (eg, seborrheic dermatitis, atopic dermatitis, folliculitis, or psoriasis). The description of 14 Malassezia species and subsequent worldwide epidemiologic studies did not reveal pathogenic species but rather disease-associated subtypes within species. Emerging evidence demonstrates that the interaction of Malassezia yeasts with the skin is multifaceted and entails constituents of the fungal wall (melanin, lipid cover), enzymes (lipases, phospholipases), and metabolic products (indoles), as well as the cellular components of the epidermis (keratinocytes, dendritic cells, and melanocytes). Understanding the complexity of their interactions will highlight the controversies on the clinical presentation of Malassezia-associated diseases and unravel the complexity of skin homeostatic mechanisms.

Hospital-related outbreaks due to rare fungal pathogens: a review of the literature from 1990 to June 2011

Fungi can cause severe infections. Two or more nosocomial unusual fungal infections diagnosed in a short period should be assumed as an outbreak. The review's aim was to collect data to improve their management. The free online worldwide database for nosocomial outbreaks ( http://www.outbreak-database.com ) and the PubMed/MEDLINE database were used to collect the English literature published from 1990 to June 2011. The more common Candida spp. and Aspergillus spp. infections were excluded. For each outbreak, the following data were reviewed: species, duration, source and site of infection, ward, risk factors, number of patients infected, treatment, related mortality, type of epidemiological study and time elapsed between index cases and second cases. Thirty-six reports were considered: yeasts caused the majority of the outbreaks (16 out of 36). The median values for the overall duration, number of infected people per outbreak and infection-related mortality were 5 months, 4 and 20 %, respectively. Eighteen cases were caused by contaminated substances and 13 cases were hypothesised as human-transmitted. Nosocomial outbreaks due to rare fungal pathogens involve few patients but have high related mortality. These results could be explained by the diagnostic delay, the inability of recognising the source of the infections and the challenges of the treatment. More efforts should be concentrated to implement the application of proper hygiene practices to avoid human-human transmission.

The Malassezia genus in skin and systemic diseases

In the last 15 years, the genus Malassezia has been a topic of intense basic research on taxonomy, physiology, biochemistry, ecology, immunology, and metabolomics. Currently, the genus encompasses 14 species. The 1996 revision of the genus resulted in seven accepted taxa: M. furfur, M. pachydermatis, M. sympodialis, M. globosa, M. obtusa, M. restricta, and M. slooffiae. In the last decade, seven new taxa isolated from healthy and lesional human and animal skin have been accepted: M. dermatis, M. japonica, M. yamatoensis, M. nana, M. caprae, M. equina, and M. cuniculi. However, forthcoming multidisciplinary research is expected to show the etiopathological relationships between these new species and skin diseases. Hitherto, basic and clinical research has established etiological links between Malassezia yeasts, pityriasis versicolor, and sepsis of neonates and immunocompromised individuals. Their role in aggravating seborrheic dermatitis, dandruff, folliculitis, and onychomycosis, though often supported by histopathological evidence and favorable antifungal therapeutic outcomes, remains under investigation. A close association between skin and Malassezia IgE binding allergens in atopic eczema has been shown, while laboratory data support a role in psoriasis exacerbations. Finally, metabolomic research resulted in the proposal of a hypothesis on the contribution of Malassezia-synthesized aryl hydrocarbon receptor (AhR) ligands to basal cell carcinoma through UV radiation-induced carcinogenesis.

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.

[Malassezia folliculitis: characteristics and therapeutic response in 26 patients]

BACKGROUND

Malassezia folliculitis is most often described in patients living in hot and humid countries or in immunocompromised patients. Its frequency in France is unknown. We report 26 cases diagnosed at Saint-Louis Hospital between May 2002 and April 2004. The clinical features, the contributing factors, the results of direct mycological examination and/or histology and the efficacy of antifungal treatments were compared to the literature.

PATIENTS AND METHODS

The inclusion criteria were the presence of folliculitis on the trunk confirmed by direct microscopy and/or histopathology showing abundant yeast cells in the follicles.

RESULTS

Patients comprised 22 men and 4 women (M/F sex ratio: 5: 5) with a mean age of 46 years. Five patients (19%) were immunocompromised. In normal patients, the duration of folliculitis was long with a mean of 61 months. The eruption was typical, with follicular papules and superficial pustules distributed predominantly on the trunk. Itching was frequent (70%). Direct microscopy was more often positive than histology (89% vs 33%). Some sixty-five percent of the patients had been previously treated by topical or systemic antibiotics or anti-acne drugs, which was ineffective in all cases. Cure with topical ketoconazole, oral ketoconazole alone or in combination with topical ketoconazole occurred respectively in 12%, 75% and 75% of patients, but with consistent recurrence within 3 to 4 months after cessation of treatment.

DISCUSSION

Malassezia folliculitis is probably misdiagnosed, as suggested by the long time between onset and diagnosis and the high frequency of non-antifungal treatments prescribed. In our study, direct mycological examination provided more effective diagnosis than histology. Treatment is difficult especially because of the high frequency of relapses.

CONCLUSION

A diagnosis of Malassezia folliculitis should be considered in young adults or immunocompromised patients with an itching follicular eruption. Further therapeutic trials are needed due to the frequency of relapse.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Update on the genusMalassezia

Malassezia yeasts are commensals of normal human skin, but also cause pityriasis versicolor, seborrhoeic dermatitis and evidence is accumulating that they play a significant role in atopic eczema/dermatitis syndrome (AEDS; formerly atopic dermatitis). The taxonomy of the genus has changed considerably and is likely to change more in the future. Our understanding of the interaction between Malassezia and the host demonstrates that it has the paradoxical ability to both stimulate and suppress the immune response directed against it and there is a fine balance in its existence at the interface between commensalism and pathogenicity.

Biofilm development by clinical isolates ofMalassezia pachydermatis

Malassezia pachydermatis fungemia has been reported in patients receiving parenteral nutrition. Biofilm formation on catheters may be related to the pathogenesis of this mycosis. We investigated the biofilm-forming ability of 12 M. pachydermatis strains using a metabolic activity plate-based model and electronic microscopic evaluation of catheter surfaces. All M. pachydermatis strains developed biofilms but biofilm formation showed variability among the different strains unrelated to their clinical origin. This study demonstrates the ability of M. pachydermatis to adhere to and form biofilms on the surfaces of different materials, such as polystyrene and polyurethane.

Malassezia pachydermatis carriage in dog owners

Malassezia pachydermatis is commonly carried on the hands of dog owners and may cause disease in immunocompromised persons.

Yeasts of the genus Malassezia serve as both commensal microorganisms and pathogens on the skin of humans and domestic animals. Although rare, cases of life-threatening fungemia in people have been attributed to Malassezia pachydermatis, for which dogs are a natural host. Zoonotic transfer has been documented from dogs to immunocompromised patients by healthcare workers who own dogs. We investigated the role of pet dogs as risk factors for mechanical carriage of M. pachydermatis on human hands. Dogs and their owners were sampled as pairs, by fungal culture and nested polymerase chain reaction (PCR). Although fungal culture was not a reliable means by which to detect carriage of the yeast on human hands, PCR identified M. pachydermatis on most (≈93%) human participants. Human carriage of ubiquitous opportunistic pathogens such as M. pachydermatis underscores the importance of good hand hygiene by healthcare professionals.

Malassezia species in skin diseases

Since the taxonomic revision carried out in 1996, enlarging the genus Malassezia to comprise seven different species, a number of studies have investigated from different points of view -- mycological, molecular and immunological -- the relationships of these species with the pathologies associated with lipophilic yeasts, as well as its presence in healthy skin. From these studies, it now appears clear that Malassezia globosa is the main species associated with pityriasis versicolor, which is the only cutaneous disease in which the involvement of Malassezia is undisputed. Nevertheless, this species can also be found in normal skin, in which the predominant species is Malassezia sympodialis. In the remaining dermatological disorders related to Malassezia, the role of these yeasts is controversial. In seborrhoeic dermatitis, atopic dermatitis and folliculitis, several studies have focused on the immunological aspects that could explain the pathogenic mechanism. In other diseases, such as confluent and reticulate papillomatosis, neonatal pustulosis, otitis and onychomycosis, the presence or significance of Malassezia is still a matter of dispute.

Identification of Malassezia species from patient skin scales by PCR-RFLP

OBJECTIVE

This study was aimed at the development of a DNA-based procedure directly applicable to pathological skin scales and at the assessment of its value in rapid laboratory confirmation and identification of each of the seven Malassezia species. These lipophilic basidiomycetous yeasts in predisposed individuals are involved in pityriasis versicolor, seborrheic dermatitis, blepharitis, folliculitis, atopic dermatitis and fungemia. Standard identification procedures to species level are available, but so far no system for direct detection and characterization of Malassezia species in clinical specimens is available.

METHODS

Malassezia DNA was extracted from pathological skin scales by a modified hexadecyltrimethylammonium bromide (CTAB) method and amplified by single and nested polymerase chain reaction (PCR), assays using the general fungal ITS 1/4 and 3/4 primers for amplification of sequences from the Malassezia major ribosomal DNA complex. Restriction fragment length polymorphism (RFLP) analysis of PCR products was used in subsequent species identification. DNA extracted from culture-positive skin scales was also tested by PCR and the RFLP patterns obtained were analyzed.

RESULTS

A total of 36 isolates were tested. Distinct pure culture and skin-scale ITS 3/4 HinfI and AluI restriction patterns differentially identified M. furfur, M. globosa, M. restricta, M. sympodialis, M. pachydermatis, M. obtusa and M. slooffiae. Malassezia DNA was extracted from pathological skin scales and RFLP identified solitary and multiple Malassezia species in the same specimen. Molecular identification was confirmed by cultures and biochemical tests. Concurrent detection and identification of Candida and Yarrowia species was also feasible from skin scales.

CONCLUSION

The proposed method, described for the first time, could provide a sensitive and rapid detection and identification system for Malassezia species, which may be applied to epidemiological surveys and routine practice.

Immunology of diseases associated with Malassezia species

Malassezia species are members of the human cutaneous commensal flora, in addition to causing a wide range of cutaneous and systemic diseases in suitably predisposed individuals. Studies examining cellular and humoral immune responses specific to Malassezia species in patients with Malassezia-associated diseases and healthy controls have generally been unable to define significant differences in their immune response. The use of varied antigenic preparations and strains from different Malassezia classifications may partly be responsible for this, although these problems can now be overcome by using techniques based on recent work defining some important antigens and also a new taxonomy for the genus. The finding that the genus Malassezia is immunomodulatory is important in understanding its ability to cause disease. Stimulation of the reticuloendothelial system and activation of the complement cascade contrasts with its ability to suppress cytokine release and downregulate phagocytic uptake and killing. The lipid-rich layer around the yeast appears to be pivotal in this alteration of phenotype. Defining the nonspecific immune response to Malassezia species and the way in which the organisms modulate it may well be the key to understanding how Malassezia species can exist as both commensals and pathogens.

The spectrum of Malassezia infections in the bone marrow transplant population

A consecutive series of 3044 patients who underwent BMT at the University of Minnesota over a 25 year period were reviewed for the post-transplant occurrence of infection caused by the yeast Malassezia furfur. Six patients, ranging in age from 1 to 54 years, developed Malassezia infections at a median of 59 days post transplant. Five patients were allogeneic transplant recipients; the remaining patient had undergone autologous transplantation. A spectrum of clinical manifestations of Malassezia infection was seen in these patients, including infections of mucosal surfaces and the skin, in addition to catheter-related fungemia. Unlike many of the other more common opportunistic fungal infections in immunocompromised patients, neutropenia and the use of broad-spectrum antimicrobials do not appear to be significant risk factors for Malassezia infections in the BMT population. In addition, disseminated fungal infection despite the presence of fungemia is uncommon. Lastly, the outcome of Malassezia infections in these patients, whether folliculitis, mucosal infection, or fungemia, appears to be quite favorable, in contrast to the poorer outcome with many other fungal infections in BMT patients. Catheter removal and discontinuation of intravenous lipids are important for a successful outcome in fungemic cases.

Epidemiology of nosocomial outbreaks: 14-year experience at a tertiary-care center

Twelve nosocomial outbreaks over 14 years at a tertiary-care center in Mexico are described. Overall mortality was 25.8%, one half due to pneumonia. The most common organism was Pseudomonas aeruginosa. Incidence was three outbreaks per 10,000 discharges; outbreak-related infections comprised 1.56% of all nosocomial infections. Incidence in the intensive care unit was 10-fold higher.