The Demon Under the Microscope, page 5
The new medicine Domagk learned was very complex, yet much of it could be boiled down to a simple guideline: When in doubt, leave the patient alone. Let the body heal itself. The more researchers learned about the human body—its marvelous machinery for repairing itself; its ability to shake off, in many cases, the worst diseases; its delicately balanced metabolism capable of maintaining temperature, salt levels, hormones all within very exact limits; the complex and highly effective defenses it mounted against invading microorganisms—the clearer it became that the doctor’s most important jobs were to offer comfort and stand aside. Physicians lessened pain and relieved suffering; took away some fear by explaining to patients and their families what was happening and predicting what to expect next; provided good nursing, the “tenderest care,” as one physician of the day put it; watched, waited, and hoped for the best. They had no tools with which to do anything else. Once an infectious disease started in the body, there were no drugs that could stop it (with the sole exception of quinine for malaria). In 1928, a pharmacologist estimated that of the thousand or so drugs available to physicians, only about one in ten was “by common consent deemed essential for treating the sick.” Some considered that estimate too high. One contemporary physician wrote that there were only about a dozen drugs that worked reliably in treating disease in the 1920s, notably aspirin, insulin, quinine, digoxin for heart failure, and a few sedatives and painkillers. Beyond that there were unproven and often dangerous “patent” medicines and folk cures. Drugs were primarily sold directly to consumers, and quack remedies flourished. Good physicians developed a healthy mistrust of all drug claims, regardless of their source.
Because they could not cure, physicians had to be compassionate more than powerful, humanist more than scientist, care provider more than god. There was a basic humility among physicians in those days. “Whether you survived or not depended on the natural history of the disease itself,” wrote the American physician Lewis Thomas, who earned his M.D. about the same time as Domagk. “Medicine made little or no difference.”
Many physicians believed that the situation was unlikely to change. There was an underlying pessimism in medical schools about the chances of ever finding effective drugs, and there was an unwillingness to waste time trying. A physician doing drug research was a physician taken away from patient care. There was an unsavory aspect to a physician’s developing a drug for money. There were ethical questions about testing drugs on patients. Developing new drug therapies smacked of a return to the discredited age of bleedings and purgings. New drugs in any case came mostly out of private firms and were sold with hyperbole at best and lies at worst; a physician’s task was to sort through the dubious claims and push away the hucksters selling them. Medical education stressed understanding the body, accurately identifying diseases (the art of diagnosis), and providing supportive care. Young doctors in training did not need to be bothered with new drug theories. The men and women of medicine during that time were, as one historian put it, “therapeutic nihilists.”
ANTONI VAN LEEUWENHOEK was a scientific superstar. The greats of Europe traveled from afar to see him and witness his wonders. It was not just the leading minds of the era—Descartes, Spinoza, Leibnitz, and Christopher Wren—but also royalty, the prince of Liechtenstein and Queen Mary, wife of William III of Orange. Peter the Great of Russia took van Leeuwenhoek for an afternoon sail on his yacht. Emperor Charles of Spain planned to visit as well but was prevented by a strong eastern storm.
It was nothing that the Dutch businessman had ever expected. He came from an unknown family, had scant education, earned no university degrees, never traveled far from Delft, and knew no language other than Dutch. At age twelve he had been apprenticed to a linen draper, learned the trade, then started his own business as a fabric merchant when he came of age, making ends meet by taking on additional work as a surveyor, wine assayer, and minor city official. He picked up a skill at lens grinding along the way, a sort of hobby he used to make magnifying glasses so he could better see the quality of the fabrics he bought and sold. At some point he got hold of a copy of Micrographia, a curious and very popular book by the British scientist Robert Hooke. Filled with illustrations, Micrographia showed what Hooke had seen through a novel instrument made of two properly ground and arranged lenses, called a “microscope.” Hooke’s device was simple and weak, something on the order of a child’s toy today, but it was good enough to see previously invisible details of the structure of insects, bird feathers, cheeses, and sponges. Hooke’s lenses disclosed a common flea “adorn’d with a curiously polished suite of sable Armour, neatly jointed,” and a thin slice of cork “all perforated and porous, much like a Honey-comb” (this was the first description of plant “cells,” a term Hooke coined). Micrographia was an international bestseller in its day. Samuel Pepys stayed up until 2:00 A.M. one night poring over it, then told his friends it was “the most ingenious book that I ever read in my life.”
Van Leeuwenhoek, too, was fascinated. He tried making his own microscopes and, as it turned out, had talent as a lens grinder. His lenses were better than anyone’s in Delft; better than any Hooke had access to; better, it seemed, than any in the world. The microscopes he made—small by today’s standards, smaller than a hand—were far more powerful than Hooke’s. With them he started looking at everything: bees’ mouth parts, lice, fungi. He found that he could see more and much smaller things than Hooke had seen. He went beyond Hooke, turned his lenses on blood and spittle, paper and snow, linen, chalk, sugar, vinegar, tears, soap, bile, seeds, sweat, the liver of a sheep, the eye of a cow, hair from the tail of an elephant. He saw crystals form in evaporating salt water. He saw poison ooze from the sting of a scorpion.
Then, in the summer of 1675, he looked deep within a drop of water from a barrel outside and became the first human to see an entirely new world. In that drop he could make out a living menagerie of heretofore invisible animals darting, squirming, and spinning. He did not quite believe his eyes and for a time kept his notes to himself. At last, when he was sure, he published his findings, announcing the discovery of what he called extremely tiny “animalcules,” “wee beasties,” each with its own unique method of locomotion, what looked like tiny arms or fins waving, tails whipping, rotating, tumbling, zooming. They seemed to come in all sizes. The closer he looked, the finer the lenses he used, the smaller and smaller animalcules he saw. There seemed to be no end to them. It was then that the greats of the era began making their way to Delft to look through van Leeuwenhoek’s magic lenses.
He kept looking at other things as well. He was interested in seeing, for instance, if something in the way spices were built could be related to their effect in the mouth. Perhaps, he thought, pepper might get its bite from little spikes on its surface. He softened some pepper in water to better study it and on April 24, 1676, turned the best of his microscopes to the pepper water. There he found, at the very limits of his vision, what seemed to be living things far tinier than any he had ever seen before, so infinitesimal that he judged that “thirty millions of these animalcules do not cover as much space as a coarse sandgrain.” It was humanity’s first look at bacteria. Using his best lenses, he began finding them everywhere—in dirt, in water fresh and salt. The scrapings from his teeth were a particularly rich source. He hired a local artist to draw what he saw and sent his findings to the greatest scientific body of the day, the Royal Society in London.
Van Leeuwenhoek’s raising of the curtain on a new world was greeted with what might kindly be called a degree of skepticism. Three centuries later a twentieth-century wit wrote a lampoon of what the Royal Society’s secretary might well have responded:
Dear Mr. Anthony van Leeuwenhoek,
Your letter of October 10th has been received here with amusement. Your account of myriad “little animals” seen swimming in rainwater, with the aid of your so-called “microscope,” caused the members of the society considerable merriment when read at our most recent meeting. Your novel descriptions of the sundry anatomies and occupations of these invisible creatures led one member to imagine that your “rainwater” might have contained an ample portion of distilled spirits—imbibed by the investigator. Another member raised a glass of clear water and exclaimed, “Behold, the Africk of Leeuwenhoek.” For myself, I withhold judgment as to the sobriety of your observations and the veracity of your instrument. However, a vote having been taken among the members—accompanied, I regret to inform you, by considerable giggling—it has been decided not to publish your communication in the Proceedings of this esteemed society. However, all here wish your “little animals” health, prodigality and good husbandry by their ingenious “discoverer.”
The satire was not far from the truth. Although very interested in the Dutchman’s discoveries, so many English scientists were doubtful about his reports that van Leeuwenhoek had to enlist an English vicar and several jurists to attest to his findings. Then Hooke himself confirmed them. All doubt was dispelled. The invisible world and its myriad minuscule denizens were real. Several generations of scientists spent the next two hundred years sorting and classifying the microorganisms, trying to see what it all meant and how it fit with the rest of the world—the visible, known world. Some of the early work was, in retrospect, amusing. Dedicated researchers, their eyes blurry from looking through primitive microscopes, thought they saw lips on the microbes, tiny eyes or mouths. Some believed there was only a single type of bacterium that changed depending on its environment.
For a long time, this meant little to medicine. The problem was that bacteria—the pepper-water animalcules, the very smallest beasts van Leeuwenhoek could see—lived profligately, in huge, chaotically mixed bunches, neighborhoods and cities and nations of bacteria. Look at the scrapings from human teeth mixed with a bit of water and even van Leeuwenhoek could make out a swarm of one or two dozen different types of bacteria (today, with better equipment, we know that hundreds of different types of bacteria can be found in the human mouth), all mixed together with dead cells and unclassifiable flotsam and jetsam. It was not until the 1870s that a French chemist named Louis Pasteur did some ingenious work linking the invisible world to disease, demonstrating that both fermentation—the making of wine and beer—and putrefaction—the rotting of meat—were due to the action of yeasts and bacteria. If bacteria could rot meat, Pasteur reasoned, they could cause diseases, and he spent years proving the point. Two major problems hindered the acceptance of his work within the medical community: First, Pasteur, regardless of his ingenuity, was a brewing chemist, not a physician, so what could he possibly know about disease? And second, his work was both incomplete and imprecise. He had inferred that bacteria caused disease, but it was impossible for him to definitively prove the point. In order to prove that a type of bacterium could cause a specific disease, precisely and to the satisfaction of the scientific world, it would be necessary to isolate that one type of bacterium for study, to create a pure culture, and then test the disease-causing abilities of this pure culture.
In theory all that was needed was to find a way to separate a single bacterium out of the mass, isolate it, feed it, and allow it to multiply (no sex necessary; most bacteria simply divide to multiply). Growing bacteria is easy: Anyone can leave a flask of warm beef broth open on a table and return a day or two later to find it cloudy with billions of bacteria. But it would be a chaotic mix of types. To study bacteria it would be necessary to isolate a single one and let it grow into a pure culture. Selecting out one kind of bacterium with the tools available in Pasteur’s day, however, was like trying to pick up a single grain of sand with a steamshovel. So Pasteur’s idea—his “germ theory” that claimed infectious diseases were caused by bacteria—remained just one of many explanations of the source of infectious disease in medicine, along with “crowd poisoning” (disease spread by emanations of respiration), diseases caused by effluvia from the skin, spontaneous generation of worms and fungi, decomposing excreta, and diminished oxygen. Before it could be proven that bacteria caused disease, it would be necessary to find some way to study them in pure culture.
The man who made that possible was Robert Koch, a small, nearsighted German physician with a rural practice in Prussia. For his twenty-eighth birthday in 1871, Koch’s wife bought him a microscope, and, like van Leeuwenhoek, Koch started looking at everything. In drops of blood taken from sheep and cows that had died of anthrax, he saw what he thought might be bacteria: threads and rods that he could not find in the blood of healthy animals. Of course he had read about Pasteur and the idea that bacteria might cause disease, but Pasteur’s germ theory was just that: a theory. Now as Koch began thinking about the problem, it fell into two parts: First, how could he determine if these threads and rods he was seeing were actually bacteria and not some bits of broken-up detritus in the blood; and second, if they were bacteria, how could he prove that they were causing anthrax? He was a small-town doctor. He knew only what he had been taught in medical school (which included next to nothing about bacteria) and what he’d read. He had no equipment. So he improvised. He did not have syringes, so he sterilized slivers of wood by heating them in the oven, dipped the slivers into the blood of anthrax-infected sheep and cows, and pricked the bacteria into healthy mice. The mice died. He opened up their bodies and examined the organs: They had the same signs of infection, the same swollen, blackened spleens found in anthrax-infected sheep and cows. Their blood was swarming with threads and rods. He then used his splinters to transfer blood from the dead mice to healthy ones, again passing the disease. Still, this was not definitive proof that bacteria caused anthrax. The blood he was using, even a tiny drop, was a mixture of thousands of bits and pieces of cells, what might be other bacteria, what might be motes dancing before his eyes. It seemed logical that his rods and threads were alive and multiplying and causing anthrax, but this was no way to prove it. He needed to separate the suspected bacteria from whatever else was in the blood. He needed a pure culture.
The solution came through the eye of an ox. From its interior he drew a few drops of clear liquid that he figured might make a good growth medium for bacteria. He examined the liquid closely under his microscope and found the field clear and empty, no bacteria that he could see. It was sterile. Then he carefully added to this growth medium tiny bits of spleen from a mouse that had been infected with anthrax. After a few days, he found the eye liquid teeming with rods and threads. Dead cellular garbage would not grow like this; it appeared that his rods and threads were live bacteria. He then used the bacteria-rich ox-eye liquid to infect other animals, finding that rods and threads transferred on the end of a splinter jabbed into a test animal would kill it in a few days, the dead body swarming with billions more rods and threads. Koch studied the bacteria and became an anthrax specialist, the first to see the rods and threads produce spores, the first to postulate ideas about anthrax transmission, forgetting now, mesmerized by his microscopic world, about his local patients. He believed he had proven that bacteria—a single type of bacterium—caused a specific disease. Regardless of the fact that he had no standing in the field of bacteriology, he began publishing his findings. His articles, carefully written, logically presented, began to convince others.
One germ = one disease was a simple and powerful concept but, even after Koch’s first discoveries, a difficult one to prove definitively until better ways could be found to create pure cultures of more types of bacteria. Early bacteriologists designed one Rube Goldberg contraption after another to separate and purify bacteria. Many depended on taking a very small sample of infected material, as Koch had, and growing it in liquid, then taking a very small sample of that and growing it again, repeating the process until just one type of bacterium could be found. Koch had managed to do it. But others found it nearly impossible. No matter how ingenious the machinery, how careful the researchers, they kept ending up with beakers of mixed bacteria. The inability to get anything but mixed cultures led many scientists to believe that bacteria had to be in mixed groups in order to thrive, that they could never be separated, perhaps that they were capable of changing from one type into another.
Then came Koch’s potato. The country doctor, his achievements already recognized and rewarded by appointment to a prestigious position in Berlin, able to hire assistants and run a large research facility, stumbled across the answer to his research questions in the form of the cut half of a boiled potato. It was sitting forgotten on a table. Just the kind of thing to bring contamination into the lab. He picked it up to throw it away. Then he noticed a sprinkling of dots of various sizes and colors on the cut surface. Curious about what was growing, he used a bit of wire to pick a smidgen from one of the dots and examined it under the microscope. He saw bacteria, multitudes of them. But it was not a mix. They were all identical. He cleaned his equipment, picked a bit from a different dot, and looked again: again bacteria, and all again identical. Each dot, he recognized, was a pure culture. Then he realized what was happening. Single bacteria in the air were drifting onto the surface of the potato, sticking in place, feeding and multiplying, the one dividing into two, the two into four, four to eight, creating a crowd of direct descendants, a growing dot, a colony, each colony descended from a single bacterium. Each dot a pure culture. The trick was using solid food instead of a liquid. He and his assistants quickly explored the idea by gently touching the ends of sterilized wires into mixes of bacteria and then streaking them out on a plate layered with food. They needed a flat surface that grew bacteria easily, so they experimented with gelatins blended with meat broths and nutrient mixes, a sort of kitchen cookery in which the mixtures were heated until they were sterile, then poured into plates to cool. Across the solid gelatin, they streaked a wire dipped into bacteria, first one way, then another, each time separating and spreading the bacteria more, getting to the point where they were pulling a few individual bacteria across the surface, each of which would grow into an individual colony, each a pure culture. One of Koch’s students, R. J. Petri, designed a shallow glass plate with a removable top to keep out contaminating bacteria, the first petri dish. Another in Koch’s lab found the ideal growth medium, a dried seaweed extract from Asia that could be dissolved and heated together with food like sterilized whole blood or meat broths, then poured and cooled to form a solid base. The Malayan name for the seaweed was agar-agar. For the next century, agar gelatins laced with nutrients in petri dishes would become the most important tools available to bacteriologists. Koch’s techniques were simple and revolutionary. Bacteria grown in pure culture on his plates could be studied one by one, examined and sized under the microscope, characteristic shapes noted, growth rates charted, preferred diets found. And, finally, they could be linked definitively to human disease. Koch came up with a set of rules for proving the link: You first had to find the germ present in all cases of a given disease; you had to sample it from a disease victim and grow it in pure culture; you had to use the pure culture to cause the disease in a test animal (human or otherwise); you then had to isolate the same germ again from the diseased test animal; and finally you had to demonstrate that you ended up with the same type of germ you started with.
