Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broadrange PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin.Human skin is colonized by diverse microbiota, including bacteria and fungi, that can be pathogenic under particular circumstances (14, 16). Traditionally, microorganisms have been identified by culture-dependent methods; however, many species are fastidious and underrepresented in cultures from mixed microbial communities (13), whereas others cannot be cultivated under known conditions (2). Therefore, culture-independent molecular techniques have been used for the identification of microbial species within ecosystems (2, 9, 27, 42).Such methods, particularly the analysis of rRNA genes, have been employed to characterize bacterial and fungal communities associated with diverse human body sites, including intestine (11), gingiva (28,33,43), esophagus (45), vagina (65), and outer ear canal (13). As predicted, these studies revealed greater diversity, including previously undescribed organisms, than did previous analyses based on culture-dependent techniques.The application of molecular techniques has been advocated to characterize the microbiota in both healthy and diseased skin (14). To date, rRNA data have been used to identify species associated with fungal dermatoses (21,29,38,39) and PCR-based diagnostic tests have been developed (15,26,62). Psoriasis, a common dermatosis affecting about 3% of the population in industrialized countries (3), is characterized by erythrosquamous cutaneous lesions associated with abnormal patterns of keratinocyte growth and differentiation (35). Although of unknown etiology, trigger factors, including physical trauma and streptococcal infections, may provoke clinical manifestations (51). Fungal organisms, including Candida albicans (63) and Malassezia furfur (3), have also been associated with the developmen...
Oral biofilms in those with denture stomatitis are different from those who are healthy. Using a cultural-independent method (polymerase chain reaction amplifi cation and sequences compared to the GeneBank database), pooled denture biofi lm samples were characterised from ten subjects who wore dentures with no stomatitis and ten others with Newton stage II denture stomatitis. Of those phylotypes that could be represented, the proportions of the genera Streptococ-cus, Veillonella, Atopobium and Prevotella differed between those subjects who were healthy and those with stomatitis. In contrast to a previously reported cultural study, there was greater fungus diversity (Candida albicans, Candida glabrata and Candida tropicalis) in the biofi lms of those who were healthy. The authors were not able to establish 'a direct cause and effect relationship between this fungus (C. albicans) and denture stomatitis'. Implant planning and placement using optical scanning and cone beam CT technology van der Zel J M. J Prosthodont 2008; 17: 476-481 Another surgical guide to ensure predictable implant placement. A surgical guide should 1) guarantee that an implant is idealy positioned, 2) take into account the soft tissues that overlie the recipient bed, and 3) ensure that there is suffi cient vertical space to accommodate the reconstruction. The surgical guide that is described in this paper fulfi ls these criteria. The method of fabrication involves forming, on a gypsum cast, a polyvi-nylacetate template containing radio opaque markers, which is used in both the scanning and imaging procedures. The cast is then optically scanned in order to map the mucosal surface, and a replica of the opposing teeth to establish the amount of vertical space. The recipient site, is imaged using a cone-beam CT scanner. A virtual implant is then selected by reference to the bone scan, the mucosal surface and opposing teeth, all combined in one 3D view. Finally, customised guides, are fabricated to accommodate the surgical drills.
Author contributions MGDB, PCD and RK conceived and designed the study. MGDB, JFRC, HSP, JH, RR, OLB, MJB, LCP, AN, HC collected the samples and metadata. AB acquired LC-MS data. LIM led LC-MS data analysis. CC led taxonomy and metadata analysis. QZ led DNA data and multi-omics analysis. JJM performed qPCR. SJS, ME, HC, AN, AB, JJM provided additional contributions to data analysis. LIM
Home microbes track space-use and reflect a decreasing exposure to environmental microbes due to urbanization.
Yeasts from the genus Malassezia are members of the normal biota of human skin, and may play a role in dermatopathology. Our previous study of the fungal microbiota from healthy subjects and from patients with psoriasis using clone library analysis revealed the presence of five Malassezia species and four uncharacterized phylotypes. We now compared the Malassezia microbiota from six healthy body locations and two psoriatic lesions, and evaluated its stability over time using multiplex real-time PCR. Samples from each body location were obtained monthly, for 4 months. Dual-labeled probes were designed to recognize four Malassezia sp. and two uncharacterized groups, and a genus-specific probe was also developed. A good correspondence was obtained between real-time PCR data and clone library analyses. Malassezia restricta was the most abundant species in the majority of samples, and high amounts of Malassezia globosa were also detected. The uncharacterized phylotype 1 was usually detected in lower proportions, nevertheless it was present in most samples. The microbiota was host-specific and relatively stable over time. In accordance with our previous observations, no significant dichotomy between samples from healthy skin and from psoriatic lesions was found; the samples clustered according to the subject, rather than health status.
Dandruff is a prevalent chronic inflammatory skin condition of the scalp that has been associated with Malassezia yeasts. However, the microbial role has not been elucidated yet, and the etiology of the disorder remains poorly understood. Using high-throughput 16S rDNA and ITS1 sequencing, we characterized cutaneous bacterial and fungal microbiotas from healthy and dandruff subjects, comparing scalp and forehead (lesional and non-lesional skin sites). Bacterial and fungal communities from dandruff analyzed at genus level differed in comparison with healthy ones, presenting higher diversity and greater intragroup variation. The microbial shift was observed also in non-lesional sites from dandruff subjects, suggesting that dandruff is related to a systemic process that is not restricted to the site exhibiting clinical symptoms. In contrast, Malassezia microbiota analyzed at species level did not differ according to health status. A 2-step OTU assignment using combined databases substantially increased fungal assigned sequences, and revealed the presence of highly prevalent uncharacterized Malassezia organisms (>37% of the reads). Although clinical symptoms of dandruff manifest locally, microbial dysbiosis beyond clinically affected skin sites suggests that subjects undergo systemic alterations, which could be considered for redefining therapeutic approaches.
Malassezia yeasts are part of the resident cutaneous microbiota, and are also associated with skin diseases such as seborrheic dermatitis (SD). The role these fungi play in skin diseases and why they are pathogenic for only some individuals remain unclear. This study aimed to characterize Malassezia microbiota from different body sites in healthy and SD subjects from Brazil. Scalp and forehead samples from healthy, mild SD and severe SD subjects were collected. Non-scalp lesions from severe SD patients were also sampled. 5.8S rDNA/ITS2 amplicons from Malassezia sp. were analyzed by RFLP and sequencing. Results indicate that Malassezia microbiota did not group according to health condition or body area. Phylogenetic analysis revealed that three groups of sequences did not cluster together with any formally described species, suggesting that they might belong to potential new species. One of them was found in high proportions in scalp samples. A large variety of Malassezia subtypes were detected, indicating intra-specific diversity. Higher M. globosa proportions were found in non-scalp lesions from severe SD subjects compared with other areas, suggesting closer association of this species with SD lesions from areas other than scalp. Our results show the first panorama of Malassezia microbiota in Brazilian subjects using molecular techniques and provide new perspectives for further studies to elucidate the association between Malassezia microbiota and skin diseases.
The microbiota found in recurrent aphthous ulcers and in the control groups diverged markedly and the rich variety of genera found can provide a new starting point for individual qualitative and quantitative analyses of bacteria associated with this oral condition.
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