马拉色菌相关人群及正常人群耳耵聍中马拉色菌带菌情况的调查

目的调查马拉色菌相关人群及正常人群耳耵聍中马拉色菌带菌情况。方法用结晶紫染色法对96例被调查人群耳耵聍进行马拉色菌检测,同时作培养,并以标准株作对照,用生理生化方法将耵聍中分离到的79株马拉色菌进行分类。结果马拉色菌相关人群耳耵聍中马拉色菌的直接检出率为91．84％（45／49）,培养阳性率为81．63％（40／49）,其中厚皮马拉色菌8株（16．33％）,合轴马拉色菌10株（20．41％）,糠秕马拉色菌22株（44．90％）。正常人群耳耵聍马拉色菌直接检出率为89．36％（42／47）,培养阳性率为78．72％（37／47）,其中厚皮马拉色菌5株（10．64％）,合轴马拉色菌8株（17．02％）,糠秕马拉色菌23株（48．93％）,斯洛菲马拉色菌1株（2．13％）。结论马拉色菌为正常人群及马拉色菌相关人群外耳道正常菌群,两组人群中马拉色菌的分离率和菌种分布无显著性差异。     

Extracellular enzymatic activity of Malassezia spp. isolates

Extracellular enzymatic activity of different species of Malassezia spp was evaluated. Thirty-three isolates of animal origin (dogs and cats) and stock culture samples were studied. Twenty isolates of M. pachydermatis, 8 of M. furfur, 2 of M. sympodialis and M. globosa and one of M. restricta, M. obtusa and M. slooffiae were examined. The enzymatic activity was investigatedusing Api Zym system. The enzymatic patterns showed light differences. Esterase lipase, Phosphatase acid and Naphtol-AS-BI-phosphohydrolase were produced in significant amounts from most isolates excepted for M. restricta, confirming the limited enzymatic activity of this species. Data obtained from the other new species described after the revision of the genus, appear to be quite homogeneous. Dixon’s broth appeared to be a valid medium for the growth of all Malassezia spp. This revised version was published online in June 2006 with corrections to the Cover Date.     

Identification of atypical strains of Malassezia spp. from cattle and dog

Yeast species in the genus Malassezia are lipophilic with the exception of Malassezia pachydermatis. During a study of the occurrence of Malassezia species in the external ear of 964 cattle and 6 dogs in Minas Gerais, Brazil, six lipid-dependent isolates could not be identified to known species. Four isolates came from healthy cows, one from a cow with otitis, and one from a healthy dog. When tested with Tweens and Cremophor EL as single sources of lipids, the strains grew on all sources except Cremophor EL. None of the six strains hydrolyzed esculin, and all produced catalase. Pigment production from tryptophan was variable. Partial large subunit rRNA sequences were obtained for two isolates that remained viable in culture. The strain from the cow with otitis was identified as a lipid-dependent variant of M. pachydermatis, and the strain from the dog was an atypical variant of Malassezia furfur.     

Concordance between phenotypical features and PCR-REA for the identification of Malassezia spp

The genus Malassezia has been recently revised and nowadays includes 11 species that cannot always be differentiated from each other by physiological and morphological tests. This study was aimed to evaluate the correlation between a molecular method and conventional phenotypic features in the identification of Malassezia spp. To achieve this aim, 92 Argentinean clinical strains isolated between 2001 and 2005 were analyzed along with three reference strains (Malassezia furfur CBS 7019, Malassezia sympodialis CBS 7222 and Malassezia slooffiae CBS 7956). By using PCR and restriction enzyme analysis with three different DNA endonucleases (PCR-REA), the molecular method consistently identified all three reference strains and all 92 clinical isolates as follows: 63 M. sympodialis, 18 M. furfur, 10 Malassezia globosa and one Malassezia obtusa. Phenotypic studies undentified 85 clinical isolates and two of the reference strains (total agreement > 91%). In particular for M. sympodialis, M. furfur and M. globosa, the species more frequently involved in human pathology, the agreement ranged between 84 and 96%. This result suggests that phenotypic studies are suitable for the presumptive identification of important Malassezia species in the clinical medical mycology laboratories where molecular methodologies are not available.     

马拉色菌蛋白酶活性测定方法的建立及其应用

为建立检测马拉色菌蛋白酶的方法并检测不同来源菌株的蛋白酶活性 ,使用全脂牛奶平板法、BSA平板法检测 7株标准株 ,3 3株M .furfur、12株M .sympodialis、4株M .obtusa临床分离株和 2 8株M .furfur正常皮肤分离株蛋白酶活性 ,并检测温度、pH值和蛋白酶抑制剂对蛋白酶活性的影响。 7株标准株均检出蛋白酶活性 ,M .furfur临床分离株蛋白酶活性高于正常皮肤分离株 (p <0 .0 1) ,最高蛋白酶活性在 3 2℃、pH5.5时表达 ,EDTA能抑制其蛋白酶活性。全脂牛奶平板法为简便、可靠的测定马拉色菌蛋白酶活性的方法 ,蛋白酶活性与菌株的致病性相关     

Isoquinoline alkaloids from Mahonia aquifolium stem bark are active against Malassezia spp

Bioassay directed fractionation of crude extract fromMahonia aquifolium led to the isolation of fraction A (bisbenzylisoquinoline alkaloid complex, BBI) and a fraction of protoberberine alkaloids, where the major compounds berberine and jatrorrhizine were isolated as their iodides. The antifungal activity of the crude extract, two protoberberine alkaloids and BBI fromM. aquifolium stem bark were evaluated against six strains ofMalassezia spp. The compounds tested were generally found to possess only weak to moderate antifungal properties: the MICs for individual strains were in the range ≤50–≥1000 mg/L.     

Prevalence of dermatophytes and yeasts (Candida spp., Malassezia furfur) in HIV patients

The prevalence of dermatophytes and yeasts (Candida spp. and Pityrosporum spp.) was studied in 40 former drug-addicts, all of whom were HIV seropositive but otherwise had no other symptoms (2nd Stage CDC Atlanta, 1987). We considered 7 skin areas for dermatophytes and Pityrosporum spp. (scalp, forehead, nose, back, chest, groin, toe webs) and the mouth for yeasts. Dermatophytes were found in 8 (20%) and tinea pedis was the most common dermatophytosis: Tricophyton rubrum was the fungus most frequently isolated (6 cases or 15%). The HIV + group showed almost the same rate of dermatophytes colonisation compared to a group of 121 athletes and to the control group. Candida spp. was present in 27 cases (67.5%) but clinical oral lesions were evident only in 5 patients (12.5%). Statistically significant differences were found in the presence of Candida spp. in HIV patients and controls (p<0.05). The lipophilic yeast Pityrosporum ovale was evaluated with quantitative and qualitative methods. Quantitative variations were evident between HIV patients and controls. P. ovale was present in 10 cases: 3 (7.5%) of them showed dischromic lesions while in 7 cases (17.5%) no clinical symptoms were evident.     

Acinetobacter spp. as nosocomial pathogens: Epidemiology and resistance features

The genus Acinetobacter is a major cause of nosocomial infections; it is increasingly being associated with various epidemics and has become a widespread concern in a variety of hospitals worldwide. Multi-antibiotic resistant Acinetobacter baumannii, is now recognized to be of great clinical significance. Numerous reports relay to the spread of A. baumannii in the hospital settings which leads to enhanced nosocomial outbreaks associated with high death rates. However, many other Acinetobacter spp. also can cause nosocomial infections. This review focused on the role of Acinetobacter spp. as nosocomial pathogens in addition to their persistence, antimicrobial resistance patterns and epidemiology.     

Antagonistic Activity of Antimicrobial Metabolites Produced from Seaweed-Associated Bacillus amyloliquefaciens MTCC 10456 Against Malassezia spp.

Probiotics and Antimicrobial Proteins - Members of the genus Malassezia are known to be opportunistic pathogens responsible for causing skin disorders such as seborrheic dermatitis or dandruff,...     

Skin Colonization by Malassezia spp. in Hospitalized Neonates and Infants in a Tertiary Care Centre in North India

Malassezia, a skin colonizer, is associated with multiple skin disorders in adults, and cephalic pustulosis and folliculitis in children. It can cause fungemia in infants and neonates. The time and pattern of colonization, risk factors associated with colonization and causing fungemia in children, are not well understood. The prospective cohort study was conducted to determine the rate of Malassezia species colonization and associated factors in hospitalized neonates and infants. Consecutive 50 neonates and infants admitted in neonatal and pediatric intensive care units were studied. The skin swabs were collected on the day of admission and every fifth day, thereafter, till the patient was discharged or died. Putative risk factors for the colonization of Malassezia species were recorded. Isolates were identified by phenotypic methods and sequencing of the D1 and D2 region of rDNA. Neonates were not colonized at the time of entry in neonatal ICU or at birth. Nineteen (38 %) neonates were colonized with Malassezia species during their hospital stay. Among the infants, three (6 %) came to ICU with Malassezia colonization and 26 (52 %) acquired Malassezia during ICU stay. Mechanical ventilation, duration of hospital stay, central venous catheterization, and antifungal therapy were the significantly associated factors for colonization. Malassezia furfur was the most common species isolated from the skin of infants and neonates. Colonization by Malassezia species in infants and neonates in a hospital is not uncommon and can be a potential source of nosocomial infection.     

In vitro induction of genetic variability in cotton (Gossypium spp.)

Summary Through the in vitro culture of excised embryos and ovules, interspecific hybrids have been obtained from cultivated and wild species of Gossypium. The hybrids matured upon transfer to the field. The anthers, ovules and embryos from both the diploid (2n=26) and tetraploid (2n=52) species underwent proliferation, and this response was genotypic. The diploid species invariably showed profuse callusing in comparison with the tetraploid. The callus showed various chromosome numbers, ranging from haploids to hexaploids, and from high polyploidy to aneuploidy. Hybrid callus culture may augment the genetic variability by providing a means for obtaining genetic exchange in interspecific hybrids. The implications of the in vitro induction of genetic variability for cotton improvement are discussed.     

Molecular Epidemiology and Characterization of Campylobacter spp. Isolated from Wild Bird Populations in Northern England

Campylobacter infections have been reported at prevalences ranging from 2 to 50% in a range of wild bird species, although there have been few studies that have investigated the molecular epidemiology of Campylobacter spp. Consequently, whether wild birds are a source of infection in humans or domestic livestock or are mainly recipients of domestic animal strains and whether separate cycles of infection occur remain unknown. To address these questions, serial cross-sectional surveys of wild bird populations in northern England were carried out over a 2-year period. Fecal samples were collected from 2,084 wild bird individuals and screened for the presence of Campylobacter spp. A total of 56 isolates were recovered from 29 birds sampled at 15 of 167 diverse locales. Campylobacter jejuni, Campylobacter lari, and Campylobacter coli were detected by PCR, and the prevalences of different Campylobacter spp. in different avian families ranged from 0% to 33%. Characterization of 36 C. jejuni isolates by multilocus sequence typing revealed that wild birds carry both livestock-associated and unique strains of C. jejuni. However, the apparent absence of unique wild bird strains of C. jejuni in livestock suggests that the direction of infection is predominantly from livestock to wild birds. C. lari was detected mainly in wild birds sampled in an estuarine or coastal habitat. Fifteen C. lari isolates were analyzed by macrorestriction pulsed-field gel electrophoresis, which revealed genetically diverse populations of C. lari in Eurasian oystercatchers (Haematopus ostralegus) and clonal populations in magpies (Pica pica).Infection with Campylobacter spp. continues to be the leading cause of human infectious intestinal disease in the United Kingdom and has a significant economic impact (39). Consequently, there is a continuing effort to identify effective control methods. The majority of human infections (∼90%) are caused by Campylobacter jejuni subsp. jejuni (46). Other Campylobacter species, including Campylobacter coli and Campylobacter lari, can also cause enteritis in humans, but their prevalence is lower. Most C. jejuni infections are believed to result from consumption of contaminated food, including poultry meat (27, 40), red meat (52), and milk (13), which is thought to be contaminated primarily by feces. It is well established that most livestock species, including poultry, ruminants, and pigs, carry C. jejuni asymptomatically (27), making control at the farm level difficult. However, the epidemiology of C. jejuni cannot be explained solely by food-borne exposure; C. jejuni has also been isolated from a range of environmental samples, including samples of soil, water, sand, and the feces of a number of wildlife species, including wild birds (1-3). However, the role that non-food-borne exposure plays in the epidemiology of C. jejuni is currently not well defined.High prevalences of Campylobacter species infections have been found in a wide range of wild bird species, although there is great variation between taxa (2, 4, 7, 16, 35, 47, 48). Given their ability to fly long distances and their ubiquity, wild birds have the potential to play an important role in the epidemiology and evolution of Campylobacter spp. However, whether wild birds are a source of infection for humans or domestic livestock or are mainly recipients of domestic animal strains or, indeed, whether separate cycles of infection occur remain unknown. These questions remain unanswered in part because investigations of the epidemiology of Campylobacter spp. have been complicated by their high inter- and intraspecies genetic diversity (6).The methods that have been routinely used to characterize Campylobacter isolates are restricted due to genomic instability in Campylobacter populations (10, 38, 45). Multilocus sequence typing (MLST) is a method that has the advantage of being objective since it is sequence based, which allows comparison of isolates from different laboratories and accurate determination of relationships between isolates from diverse sources (11). MLST studies of C. jejuni in farm animals and the environment, including wildlife, suggest that some strains may be associated with particular host groups (6, 10, 15, 30). However, in the same studies other strains were found to occur in several host species or habitats. Few studies have investigated the molecular epidemiology of Campylobacter infection in wild bird populations using MLST, and because only a relatively small number of isolates from wild birds have been characterized by MLST, conclusions have not been drawn yet about how wild bird isolates fit into the overall phylogenetic scheme or whether wild birds act as reservoirs, amplifiers, or merely indicators of infection of domestic animals with zoonotic genotypes.In the current study a large cross-sectional survey of wild bird populations in northern England was undertaken to investigate the epidemiology of Campylobacter infection. Previous studies that have focused on the epidemiology of Campylobacter spp. solely in wild birds have investigated either a narrow range of taxonomic groups (2, 5, 17, 23, 29, 33, 43, 50) or wild birds from a limited range of habitats (18, 25, 48). Studies that have investigated a broad range of wild bird species have used Campylobacter characterization techniques that do not allow conclusions about possible host associations to be drawn or comparison of the genetic diversity of isolates between studies (21, 25, 34, 47, 53). Therefore, the aims of this study were (i) to determine the host range and prevalence of Campylobacter spp. in a wild bird population and (ii) through molecular characterization of isolates to determine whether wild birds were a likely source of infection in humans or domestic livestock and whether separate cycles of infection with host-adapted strains of Campylobacter spp. were maintained in the wild bird population.     

Malassezia Folliculitis in China

Superficial Malassezia folliculitis was diagnosed in 1-1.5% of all dermatology patients seen in a Dermatology Out-Patient clinic in Urumqi City, Xinjiang province, west China. It was most prevalent in healthy, middle-aged males in the warm seasons. This disease, first reported in 1969, is usually diagnosed as a systemic disease of immuno-compromised patients. Our findings indicate it is a relatively common superficial skin disease that can be managed with ketoconazole or itraconazole.     

Microreview of Pityriasis versicolor and Malassezia species

Recently 11 Malassezia species were isolated. Attention has focused on the relationship between Malassezia species and Malassezia-related disease. The causal fungus of Pityriasis versicolor is M. globosa. The conditions of mycelial form induction are not clear for M. globosa.     

The pathogenesis of Malassezia yeasts

The genus Malassezia includes twelve species of yeast, many of which have been mainly associated with human and canine diseases. Malassezia pachydermatis colonizes the skin and mucosal sites of healthy dogs and cats. Despite being part of the normal cutaneous microflora, Malassezia spp. yeast may become pathogenic under certain circumstances. This article reviews the factors related to both host and yeast which affect the pathogenical or commensal phenotypes of Malassezia yeasts.     

Epidemiology and molecular relationships of Cryptosporidium spp. in people, primates, and livestock from Western Uganda

Background

Cryptosporidium is one of the most common parasitic diarrheal agents in the world and is a known zoonosis. We studied Cryptosporidium in people, livestock, and non-human primates in the region of Kibale National Park, Uganda. Land use change near the park has resulted in fragmented forest patches containing small, remnant populations of wild primates that interact intensively with local people and livestock. Our goal was to investigate risk factors for Cryptosporidium infection and to assess cross-species transmission using molecular methods.

Methodology/Principal Findings

Diagnostic PCR revealed a prevalence of Cryptosporidium of 32.4% in humans, 11.1% in non-human primates, and 2.2% in livestock. In the case of humans, residence in one particular community was associated with increased risk of infection, as was fetching water from an open water source. Although 48.5% of infected people reported gastrointestinal symptoms, this frequency was not significantly different in people who tested negative (44.7%) for Cryptosporidium, nor was co-infection with Giardia duodenalis associated with increased reporting of gastrointestinal symptoms. Fecal consistency was no different in infected versus uninfected people or animals. DNA sequences of the Cryptosporidium oocyst wall protein gene placed all infections within a well-supported C. parvum/C. hominis clade. However, the only two sequences recovered from primates in the core of the park''s protected area fell into a divergent sub-clade and were identical to published sequences from C. parvum, C. hominis, and C. cuniculus, suggesting the possibility of a separate sylvatic transmission cycle.

Conclusions/Significance

Cryptosporidium may be transmitted frequently among species in western Uganda where people, livestock, and wildlife interact intensively as a result of anthropogenic changes to forests, but the parasite may undergo more host-specific transmission where such interactions do not occur. The parasite does not appear to have strong effects on human or animal health, perhaps because of persistent low-level shedding and immunity.     

Geometric morphometric study of geographic and host-related variability in Aceria spp. (Acari: Eriophyoidea) inhabiting Cirsium spp. (Asteraceae)

The russet mite, Aceria anthocoptes (Nalepa), is the only eriophyoid that has been recorded on Cirsium arvense (L.) Scop. It has been noted in several European countries and recently in the USA. In this study we explored the geographic and host-related variability of Aceria spp. inhabiting different Cirsium spp. We applied landmark-based geometric morphometric methods to study morphological variability of three body regions (ventral, coxigenital and prodorsal) of 13 Aceria spp. populations inhabiting five Cirsium spp. in Serbia (Europe) and four Cirsium spp. in Colorado (North America). Analyses of size and shape variation revealed statistically significant differences between Aceria spp. living on European native and North American native Cirsium spp., as well as between A. anthocoptes s.s. inhabiting European C. arvense and North American C. arvense. The coxigenital region was the most informative when considering inter-population shape differences. European Aceria spp. dwelling on Cirsium spp., including A. anthocoptes s.s. from C. arvense, are characterized by higher inter-population size and shape variability than their North American counterparts. This finding supports a Eurasian origin of A. anthocoptes, presumed to consist of a complex of cryptic taxa probably coevolved with host plants in the native environment. Morphological similarity among Aceria spp. inhabiting North American native Cirsium spp. may indicate that speciation of A. anthocoptes started relatively soon after the host shift to plants different from C. arvense in the invaded region.     

Association of Malassezia to Atopic Dermatitis

Purpose of Review

Atopic dermatitis (AD) is a common chronic, inherited, relapsing, inflammatory skin condition. A multifactorial etiology has been postulated, including genetic and immunological factors, impaired skin barrier function and environmental triggers, all of them are relevant in the pathogenesis. Malassezia spp. is the most common fungi of the skin microbiome. Most of the studies comparing the skin colonization with Malassezia spp. in healthy people and AD patients did not show difference between both groups. This review aims to show the studies carried out in this regard and the reported evidence about the role of Malassezia spp. in the pathogenesis of AD.

Recent Findings

The rate of IgE-mediated sensitization Malassezia spp. is very high in AD patients, mainly in adult patients and in patients with involvement in the head and neck. Different mechanisms have been postulated to explain the interaction of Malassezia spp. with human skin cells and immune cells and how its interaction contributes to the inflammation process in AD. Systemic and topical azole antifungals have been used with doubtful results showing beneficial effects in some AD patients.

Summary

There is no clear explanation for the high frequency of Malassezia spp. sensitization in AD patients in relation with healthy individuals. Further research is necessary to determine the specific role of Malassezia in AD and the indication for the use of antifungals in this disease.

     

Onychomycosis due to Malassezia.

The records of fifty patients presenting Malassezia spp. associated onychomycosis were compiled from two different mycology laboratories from Medellín, Colombia. Malassezia spp. was isolated by culture as the only etiological agent in 32% of the cases and associated to a yeast of the genus Candida in 30% of the cases. In 22% of the cases although Malassezia spp. was observed by direct examination, it was no isolated but others species were obtained. No etiological agent was isolated by culture in 16% of the cases. We found evidence of the Malassezia spp.- Candida relationship in 48% of the cases by either direct examination or by culture isolation. The level of detection of Malassezia spp. by culture isolation was of 62% as compared to the direct examination. Results showed similar patterns of distribution of epidemilogical factors for both entities: onychomycosis by Candida albicans and onychomycosis by Malassezia spp.