However, studies on the bacterial community composition of the skin of individuals with leprosy are still missing. In patients with psoriatic lesions, the most abundant phyla were Firmicutes and Actinobacteria, with Firmicutes significantly overrepresented while Actinobacteria is underrepresented comparing to healthy skins (Gao et al. In comparison to healthy individuals, atopic dermatitis patients show a higher abundance of Stenotrophomonas maltophilia, and a lower abundance of Propionibacterium acnes and Staphylococcus sp., both are resident skin bacteria (Dekio et al. Studies on the skin microbiota of individuals with non-infectious diseases, such as atopic dermatitis and psoriasis, have revealed a variation in the bacterial composition of the skin of these patients when compared to healthy persons (Gao et al. Other microbiome studies have provided insights into the delicate balance between skin health and disease (Grice et al. These studies have also uncovered the genera Corynebacterium, Propionibacterium, and Staphylococcus as abundant resident microbiota of human skin. Indeed, among the 19 bacterial phyla found so far by these studies, special attention goes to the Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes phyla, which are consistently reported and account for 99% of the 16S rRNA gene sequences. Previous studies highlight that the human skin microbiome is diverse and personalized (Grice et al. Thus, the human microbiome has been referred to as a forgotten organ (Morgan & Huttenhower 2012) New sequencing technologies are transforming the study of microbial diversity and have revealed that the human skin harbors a complex microbiota. Increasing evidence is continuously bringing to light the importance of microbiota for human general health, including its essential role in physiology, and in our immune responses and metabolism (Cho & Blaser 2012). Data reported by the (World Health Organization 2013) revealed that, in 2012, around 122 countries presented cases of leprosy with India showing the highest number of cases (134,752) followed by Brazil (33,303). This neglected tropical disease has a close relationship with poverty, being a major challenge to public health in countries where it remains endemic. It still remains a stigmatizing disease (Nascimento 2013 Degang et al. The disease displays a spectrum of clinical manifestations, such as lepromatous (multibacillar) and tuberculoid (paucibacillar) leprosy, which are attributed to the host immune response. The skin, the peripheral nerves, the nasal mucosa, eyes, and the reticulum-endothelial system are the preferred target sites for this pathogen. Mycobacterium leprae is the causative agent of leprosy, an ancient chronic infectious disease and may have severely debilitating physical, social, and psychological consequences. Our data suggest significant shifts of the microbiota with emergence and competitive advantage of potentially pathogenic bacteria over skin resident taxa. Most of the taxa found in skin from leprous lesions are not typical in human skin and potentially pathogenic, with the Burkholderia, Pseudomonas and Bacillus genera being overrepresented. Propionibacterium, Corynebacterium and Staphylococcus, resident and abundant in healthy skin, were underrepresented in skin from leprous lesions. There were considerable differences in the distribution of Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria, with the first two phyla enriched and the other markedly diminished in the leprous lesions, when compared with healthy skin. Taxonomic analysis of leprous lesions revealed main four phyla: Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, with Proteobacteria presenting the highest diversity. Here we used Sanger and massively parallel small sub-unit rRNA (SSU) rRNA gene sequencing to characterize the microbiota of leprous lesions, and studied how it differs from the bacterial skin composition of healthy individuals previously described in the literature. But while studies are continuously revealing the complexity of human skin microbiota, the microbiota of leprous cutaneous lesions has not yet been characterized. Increasing evidence has highlighted the importance of microbiota for human general health and, as such, the study of skin microbiota is of interest. Leprosy is a chronic infectious disease that remains a major challenge to public health in endemic countries.
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