Discovering an Antibiotic
Once the equipment and supplies are there, the work itself can be started. First, a large number of samples of molds and other microorganisms need to be collected. This is a lot of work, as each sample is collected from a different source, often from dirt. Penicillin was originally collected from mold from an overripe cantaloupe, by the way, not from bread or an orange.
As each sample is collected, it is placed in a test tube and transported back to the lab. The sample is swabbed onto the petri dish and placed in an incubator at body temperature. It is grown until cultures appear on the plate, which usually takes two or three days. From there, individual molds are selected and swabbed into test tubes containing diluted food for the mold. This gives pure samples which are grown for several days. Some of a given sample is taken and spun very rapidly in a centrifuge, causing the denser cells to go to the bottom of the tube, leaving what chemicals are produced by the mold in the top of the tube with water. The liquid at the top is removed very carefully with a long glass straw. This can be concentrated further in the same way that sugar is produced, by heating the mixture in a vacuum chamber. A low-tech vacuum pump can be made from the same kind of piston used on a steam locomotive, but in reverse; instead of having steam push the piston to drive the wheels, an engine pushes the piston, sucking air out through the cylinder. Another dish is swabbed with the bacteria, and then a large drop of the extract is placed in a spot in the center of the dish, and this is grown. If a circle containing no bacteria appears in the center of the culture, then this makes a possible drug. (The identification, isolation and pure culture of disease-causing bacteria to test with is yet another challenge, by the way. But that’s beyond the scope of this article.)
That’s the easy part—just lots and lots of repetition. But it is not without risk! If the people doing the work get sloppy, they could get one of the diseases they are testing against, and kill themselves and their co-workers as well. A cut from a broken test tube or petri dish, a spill of germs, and there could be trouble.
Once a mold is chosen, it needs to be grown in greater quantity, in larger bottles. A lot more extract is made and purified. It will probably be made into a powder so that it is at a consistent dosage. This is carefully measured out, and a small amount is fed to a lab mouse. If it dies, this probably isn’t a good drug. Larger amounts are fed to mice, until they figure out how much is safe for the mouse to take. Then, they infect mice with bacteria. Some are given doses of the drug by injection, with a few other mice given no drug for comparison. If the dosed mice live when the undosed mice don’t, then you have a drug that will cure mice of the disease.
A promising start. But it’s risky, because if the sick mice bite or scratch anyone, they run a very real risk of getting the disease. This process is repeated with larger animals, such as pigs or dogs. Again, if it cures the disease, it increases the likelihood that people can benefit from it.
Next is the really scary part: trying it out on people. It would be nice if the drug could be initially tested to see if it was penicillin or tetracycline, but that is beyond the Grantville high school chem lab’s capability. To start with, you need healthy people, and they must be volunteers. This is important, for both practical and moral reasons. People must know what you are doing, and what risks they are running. You start by giving a few volunteers single small doses of the drug, and see if it makes them sick. If not, then the process is continued with larger and more doses until you reach the level that it worked (per weight) in animals. At this stage, it is easily possible that they could become quite sick or even die. If it does not make the volunteers sick, then it has passed the first step in testing the drug.