Introduction
"Ring around the rosy, a pocket full of posies, ashes, ashes, we all fall down." This seemingly innocent children's nursery rhyme actually describes the pustules an infected individual might get when their body is fighting a raging infection of the bacterium Yersinia pestis. It is the microbe responsible for the Bubonic plague. The infection causes an inflammation of the lymph nodes that may eventually lead to the development of buboes (swollen lymph glands) and even worse, gangrene. Throughout human history, humans have attempted to fight their invisible enemies – the microbes. As long as stories on the nightly news discuss the latest outbreak of antibacterial resistant bacteria in a hospital, a child inadvertently harmed by E.coli contaminated broccoli, or a tourist developing flesh-eating bacteria while on holiday, microbes will continue to have a bad reputation.
Like many people, my students readily turn to television as their main source of science. This is in part due to the success of shows like Cosmos, Mythbusters, and my two favorites Dirty Jobs, and Monsters Inside Me. Science shows are easy to digest and frankly, they make for great entertainment. One memorable experience my students and I share occurred when watching a clip of the dirtiest man alive - Mike Rowe. We watched as the fearless Dirty Jobs host swabbed from head to toe. The enthusiastic microbiologists collected the seemingly innocuous swabs, swiped them onto a life-size agar medium, and incubated the agar Mike Rowe. The revelation at the end of the program showing the variety of microbial fauna that grew on the life-size cast is enough to drive the most desensitized microbiologist to grab the largest bottle of disinfectant spray. The life-size agar model was littered with various colors of grown-up microbes clearly showing the extensive harmless microbes that call our skin home.
Today, advances of DNA sequencing techniques, scanning and electron microscopes, and the development of systems and procedures for collecting, handling, and storing microbes have allowed scientists to study them to new heights. New bacterial and viral species are constantly being discovered in places both inhospitable to humans and seemingly inhospitable to any organisms. The diversity of microbes and their often higher rates of mutation and evolution, create endless points of inquiry for scientists, teachers, and students. This curriculum unit is designed to answer a small niche in microbial study – What microbes exist on the human skin? What are their beneficial or pathogenic potentials? What new discoveries will the Human Microbiome Project unveil?
To high school teenagers, the concept of microbes is simply that: "micro". Beyond the rudimentary splashing of their fingers as they depart the bathroom facilities and their vain attempts to not sneeze onto their friends, teenagers are simply unaware of the microscopic world of bacteria and viruses. Humans are a hardy species, withstanding the barrage of microbes attacking our body's systems each day. So, the question is how? How can we survive the onslaught of an enemy whose numbers are far greater than all of human kind itself? One answer is the genius design of the human integumentary system or skin. It is our body's first wall of defense against the "dirty" world we live in.
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