Pathogenic Organisms

    It is a common misconception - even in the medical community - that all bacteria are "bad," and that the only "good" bacterium is a dead one. Recently a group of student hospital aids asked doctors off-handedly if they could think of any good or harmless bacteria. Not one of the six doctors interviewed could think of any. However, those same students sought out a local lunchtime hangout frequented by local farmers. When these folk were asked the same question, they started counting off beneficial bacteria on their fingers - the nitrogen-fixing bacteria in their beans and alfalfa clover, the myriads of bacteria in the rumens of their cattle, goats and sheep, the ones that made silage, cheese, pickles, those that converted the manure into methane which was trapped and used for heating... The students were overjoyed to find that real down-to-earth folk understood the microbial underpinnings of the pyramid of life.

    However many of the students enrolled in a microbiology course have aims to join the health sciences, and would be interested in knowing more about the pathogens. The instructor here has several things to say about that:

1. Until the student has proven skills in aseptic techniques, no handling of known pathogens should be attempted. Does the student want to get sick? No! Does the instructor want to get sick? No!
2. When the time comes for working with pathogens in an advanced course, that work should be done in a recognized research facility equipped for doing such work - e.g.: the Centers for Disease Control in Atlanta, or the Walter Reed Army Institute of Research just north of Washington, DC.
3. Why work with pathogens when there are so many analogs to use? Shigella (dysentery) and Salmonella (typhoid) are such close cousins of E.coli, why not use any one of the thousands of non-pathogenic strains of E.coli? If it becomes necessary to use Shigella or Salmonella, there are many avirulent strains available to pass all of the relevant identification tests but lack several of the 48 or so virulence genes, and thus cannot make you sick.
4. Of course, there are a few in the human population who are immunocompromised and even normal symbionts of the body can wreak havoc. Those people still may participate in microbiology so long as they are warm-blooded, because many species of bacteria cannot grow at 37°c, and thus cannot infect humans or most other mammals.
5. A thought must be expressed as we must eschew anthropocentricity: are the microbes we use harmless to the environment? We might consider a bee pathogen safe for us humans to handle, but once it escapes from lab, it can wipe out bees upon which our flowering plants depend, and we depend on those plants. Thus the strains of E.coli used in this class are deemed not only harmless to humans, but in many cases necessary for our survival.
6. Summing all the above, you should read a list of organisms compiled by educators and approved by some of the nation's top pathogenic bacteriologists at the National Institutes of Health and the Walter Reed Army Institute of Research for use at all levels of education without any need for control or containment.

    Our projects: In two of the projects - the self-sterilizing surfaces and making potable water for disaster areas - our bacteria will be from common garden soil. How many of you have gotten sick playing in the dirt and eating it as little kids? In the vaccine project, we shall be using temperature-sensitive mutants that can only grow at less than 35°c. Again, these "ts-mutants" cannot grow in your bodies.

    So rest easy: the organisms you will be handling are safe. Just don't scald yourself with hot agar solutions, cut yourself on broken glass, or stare into UV lights.