Tuesday, 23 July 2013

New ecological map of the human body

An interesting paper has been published in Nature by Keisha Findley et al, titled: "Topographic diversity of fungal and bacterial communities in human skin". The paper has been published in Nature.

The abstract reads:

"Traditional culture-based methods have incompletely defined the microbial landscape of common recalcitrant human fungal skin diseases, including athlete’s foot and toenail infections. Skin protects humans from invasion by pathogenic microorganisms and provides a home for diverse commensal microbiota1. Bacterial genomic sequence data have generated novel hypotheses about species and community structures underlying human disorders2, 3, 4. However, microbial diversity is not limited to bacteria; microorganisms such as fungi also have major roles in microbial community stability, human health and disease5. Genomic methodologies to identify fungal species and communities have been limited compared with those that are available for bacteria6. Fungal evolution can be reconstructed with phylogenetic markers, including ribosomal RNA gene regions and other highly conserved genes7. Here we sequenced and analysed fungal communities of 14 skin sites in 10 healthy adults. Eleven core-body and arm sites were dominated by fungi of the genus Malassezia, with only species-level classifications revealing fungal-community composition differences between sites. By contrast, three foot sites—plantar heel, toenail and toe web—showed high fungal diversity. Concurrent analysis of bacterial and fungal communities demonstrated that physiologic attributes and topography of skin differentially shape these two microbial communities. These results provide a framework for future investigation of the contribution of interactions between pathogenic and commensal fungal and bacterial communities to the maintenance of human health and to disease pathogenesis."

One interesting thing from the paper is in relation to fungi. The team found an average of 50 species of fungi living on the feet of 10 healthy adults. For the study, the scientists also swabbed other body part of the volunteers. Sites selected included behind the ear, between the eyebrows, and on the chest, back, nostril, scalp, and various parts of the arm.
However, fungal communities were most diverse on the foot. The diversity was not such in numbers and types for any one moment in time, for when the researchers re-sampled the study volunteers a couple of months later they found that the fungal communities had changed and different species were found. This is unlike other parts of the body, where the fungal types were relatively stable.
The parts of the foot showing the greatest diversity were the plantar heel, toenail and toe web.

For further details about this study, see Pharma Micro.

Posted by Tim Sandle