Picture: A swab taken from the forearm 
Every person has unique
bacterial species; © Geo Blaser

Not only were the bacteria more diverse than previously estimated, but some of them had not been found before, says Martin J. Blaser, M.D., Frederick King Professor and Chair of the Department of Medicine and Professor of Microbiology at New York University Medical Center and School of Medicine (NYU) School of Medicine, one of the authors of the study.

In the study, the researchers took swabs from the inner right and left forearms of six individuals. The researchers wanted to be able to compare two similar parts of the body. Because they also wanted to study change over time, they took swabs from four of the individuals 8 to10 months after the first test.

Roughly half, or 54.4%, of the bacteria identified in the samples represented the genera Propionibacteria, Corynebacteria, Staphylococcus and Streptococcus, which have long been considered more or less permanent residents in human skin.

The six individuals differed markedly in the overall composition of the bacterial populations on their skin. They only had four species of bacteria in common: Propionibacterium acnes, Corynebacterium tuberculostearicum, Streptococcus mitis, and Finegoldia AB109769. "This is a surprise," says Zhan Gao, M.D., senior research scientist in Dr. Blaser's lab. "But many things affecting the skin affect bacteria, such as the weather, exposure to light, and cosmetics use."

Almost three-quarters, or 71.4%, of the total number of bacterial species were unique to individual subjects, suggesting that the skin surface is highly diversified in terms of the bacteria it harbours, according to the study.

Three bacterial species were only found in the male subjects: Propionibacterium granulosum, Corynebacterium singulare, and Corynebacterium appendixes. While the sample is too small to draw conclusions, the scientists believe that women and men may harbour some different bacterial species on their skin.

MEDICA.de; Source: New York University Medical Center and School of Medicine