Scientists Surprised by Diversity of Skin Bacteria

This illustration shows the 20 sites on the human body that were targeted for microbial genome sequencing analysis. (Credit: Jane Ades/NHGRI)

This illustration shows the 20 sites on the human body that were targeted for microbial genome sequencing analysis. (Credit: Jane Ades/NHGRI)

Researchers recently discovered that the diversity of bacteria on human skin is much greater than previously thought. The research, conducted by scientists from the National Human Genome Research Institute (NHGRI), National Cancer Institute (NCI), and the National Institutes of Health (NIH) Clinical Center.

In the study, skin samples were taken from twenty different locations on the bodies of ten healthy volunteers. The sites on the body were specifically chosen due to each location’s propensity to develop skin disorders. The sites were categorized into three different microenvironments: oily, moist, and dry. Oily sites included locations beside the nose and inside the ear; moist sites included the armpit and inner elbow; and dry sites included the inside surface of the mid-forearm and the palm of the hand.

After collecting the skin samples, the scientists used modern DNA sequencing techniques and computational analysis to determine the diversity of skin bacteria. After DNA was extracted from each sample, the scientists sequenced the 16S rRNA genes (a type of gene specific to bacteria).

In their analysis, the scientists identified over 112,000 different bacterial gene sequences. The sequences were then classified and compared–this led to the classification of skin bacteria into 19 different phyla and 205 different genera. The scientists found that the greatest diversity of bacteria occur on the forearm and the smallest diversity of bacteria are found behind the ear. In addition, the scientists discovered that the biggest influence on bacterial diversity is body location. That is, the skin bacteria on the back of your arm are more similar to the skin bacteria on the back of someone else’s arm than they are to the skin bacteria on the front of your arm.

More to Explore

Scientists Shed Light on How Superbugs Spread

Scientists used fluorescent microscopy to capture live images of the spread of a superbug pathogen. (Credit: iStockphoto.com)

Scientists used fluorescent microscopy to capture live images of the spread of a superbug pathogen. (Credit: iStockphoto.com)

Researchers at the Oklahoma Medical Research Foundation (OMRF) have captured the first visual evidence of how deadly pathogens called “superbugs” spread. According to the researchers, these superbugs have become more and more common as the use of antibiotics has become more widespread. One of these superbugs, methicillin-resistant Staphylococcus aureus, or MRSA, was responsible for the death of 19,000 Americans over a span of just one year. Superbugs are easily transmitted but not easily treated because they resist treatment by standard antibiotics. Superbugs are most dangerous in hospitals and other health-care facilities, as patients in these locations are most susceptible to the antibiotic-resistant pathogens due to their already-impaired immune systems.

In their research, lead scientists Philip Silverman and Margaret Clark, with the help of Cindy Maddera and Robin Harris, used high-powered fluorescent microscopy to capture images of the spread of a superbug. The scientists tagged a virus with fluorescent dye, which in turn attached itself to the filaments on live bacteria. These bacterial filaments, which are thin and threadlike in appearance, are called conjugative pili. Several decades ago, scientists discovered that conjugative pili were responsible for the transmission of antibiotic resistance genes from one bacterium to another. However, no one had ever captured images of this process in progress. Silverman and Clark were the first to capture live images of the conjugative pili as they extended and retracted onto live cells, pulling cells together in preparation for genetic transfer. The results of their research will be published in the November 11 issue of Proceedings of the National Academy of Science.

The Oklahoma Medical Research Foundation is a nonprofit biomedical research institute located in Oklahoma City, Oklahoma. The goal of the foundation is to understand and develop more effective treatments for human diseases with a focus on heart disease, cancer, lupus, and Alzheimer’s disease.

More to Explore