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Outcomes of skin infection associated with bacteria already present on skin


INDIANAPOLIS — If you get a skin infection, whether it goes away on its own or you need to get medical treatment may be determined by what bacteria already make your skin their home, say scientists at the Indiana University School of Medicine.

In a study reported in mBio, a journal published by the American Society for Microbiology, the researchers found that differences in the skin microbiome — the community of microorganisms that live on the skin — were associated with differing outcomes in skin infections. In addition, the skin infections in turn led to changes in the skin microbiomes.

“This is the first prospective study to show that the skin microbiome is associated with susceptibility to skin infection and that infection outcome influences the skin microbiome,” said Stanley M. Spinola, M.D., chair and professor of microbiology and immunology at the IU School of Medicine and principal investigator for the study.

“Although this was a very small pilot study, it suggests that as analysis of the microbiome becomes more widely available, it could be used to determine who is at greater risk of infection,” Dr. Spinola said.

The researchers infected the arms of eight volunteers with the Haemophilus ducreyi, a bacteria that causes genital ulcers in Africa and Asia and disfiguring leg ulcers in children in equatorial Africa and the South Pacific. The skin microbiome was assessed before, during and after the infections. In four of the volunteers, the infections resolved on their own; the other four formed abscesses. All of the volunteers were treated with antibiotics.

The skin assessments showed that the volunteers who were able to ward off the infections easily started off with microbiomes that were similar to each other, while those who developed abscesses started with microbiomes that were much different. As the infections progressed, however, the microbiomes of those patients began to resemble each other more closely.

Dr. Spinola noted that additional research will be needed to answer such questions as which bacteria species are associated with protection from infection, and how that process works — the bacteria could be helping the immune system fight the infection or they could merely reflect an immune system that is already set up to fight the infection. Work also is necessary to determine whether fungi and viruses also play roles.

Additional investigators involved in the research included first author Julia J. van Rensburg, Evelyn Toh, Kate R. Fortney, Sheila Ellinger, Beth Zwickl, Diane M. Janowicz, Barry P. Katz, and David E. Nelson of the IU School of Medicine, and Huaiying Lin, Xiang Gao and Qunfeng Dong of Loyola University.

The research was supported by National Institutes of Health grants R01 AI27863, R01 AI27863S1 and U19 AI31494 from NIAID and by a grant to the Indiana Clinical and Translational Sciences Institute and the Indiana Clinical Research Center (UL RR052761).