UPDATED: 12/16/99 UPDATED: 12/16/99 
MICROBIOLOGY | GENETICS | MEDICAL
Ancient man recognized many of the factors involved in disease. Early civilizations on Crete, India, Pakistan and Scotland invented toilets and sewers; lavatories, dating around 2800 BC, have been found on the Orkney islands and in homes in Pakistan about the same time. One archaeologist has stated that "The high quality of the sanitary arrangements [in ~2500 BC] could well be envied in many parts of the world today". In Rome, 315 AD, the public lavatories were places where people routinely socialized and conducted business. Ten to twenty people could be seated around a room, with their wastes being washed away by flowing water; it must have been difficult to "stand on your dignity" under such circumstances. The Chinese used TOILET PAPER as early as AD 589. In Europe moss, hay and straw were used for the same purpose. I can personally attest to the use as late as 1962 of "slick magazines" as toilet paper in certain European camp grounds.
The first cities to use water pipes (of clay) were in the Indus Valley of Pakistan around 2700 BC. Metal water pipes were used in Egypt (2450 BC) and the palace of Knossos on Crete around 2000 BC had clay pipes. Rome built elaborate aqueducts and public fountains throughout its empire to insure a clean supply of water for its citizens. Rome had a "WATER COMMISSIONER" who was responsible for seeing that the water supply was kept adequate and clean; the punishment for pollution of the water supply was DEATH. Lead was commonly used for Roman pipes and the subsequent fall of the Roman empire has been related by some to the effects of lead on the Roman brain.
Most ancient peoples recognized that some diseases were communicable and isolated individuals thought to carry "infections". An example of this is the universal shunning of lepers, which occurs even today. When the Black Death struck Europe, entire villages were abandoned as people fled in an effort to escape the highly infectious plague. Similarly, in the Middle Ages the rich of Europe fled to their country homes when small pox struck in an effort to escape its terrible consequences. The fact that people who recovered from a particular disease were immune to that disease was probably recognized many different times in many places. Often these survivors were expected to nurse the ill. Greek and Roman physicians routinely prescribed diet and exercise as a treatment for ills.
Sadly, we know that this knowledge did not help most of our ancestors and that the human life span was, until the last 200 years, more often than not cut short due to infectious disease. Even today approximately 15,000,000 CHILDREN DIE PER YEAR, mainly from infectious diseases that are preventable with basic sanitation, immunization and simple medical treatments. One might honestly question just how far we have come in our treatment of disease. An excellent synopsis of the history of Microbiology (also of chemistry and general biology) can be seen by visiting this site.
Ancient people had certainly seen masses of microbes, such as mold and bacterial colonies, on spoiled food, but it is doubtful if anyone considered that they were VIEWING living organisms. Small boys and maybe a few love-sick adults staring into a clear pond, must have seen tiny specks moving rapidly about and some may have considered them living creatures, but to express this to their friends would be equivalent to us telling our friends that we'd seen a flying saucer.
The first person to report seeing microbes under the microscope was an Englishman, Robert Hooke. Working with a crude compound microscope he saw the cellular structure of plants around 1665. He also saw fungi which he drew. However, because his lens were of poor quality he was apparently unable to "see" bacteria. Using the dissecting microscope in laboratory exercises # 1 and 2 you see fungi at a magnification similar to that seen by Hooke, but without the distortion of poor lenses.
THE FIRST MICROBIOLOGIST
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Anton van Leeuwenhoek was a man born before his time. Although not the FIRST TO DISCOVER THE MICROSCOPE or to use magnifying lens, he was the first to see and describe bacteria. We know that he was a "cloth merchant" living in Delft Holland. and that he used magnifying lens to view the quality of the weave of the merchandise he purchased. He traveled to England in 1668 to view English cloth and there he saw drawings of magnifications of cloth much greater than any of the current lens available in Holland would do. He returned to Holland and took up lens grinding. Being meticulous, he developed his lens grinding to an art and in the process tested them by seeing how much detail he could observe with a given lens. One can guess that he chanced to look at a sample of pond water or other source rich in microbes and was amazed to see distinct, uniquely shaped organisms going, apparently purposefully, about their lives in a tiny microcosm. He made numerous microscopes from silver and gold and viewed everything he could including the scum on his teeth and his semen. His best lens could magnify ~300-500 fold which allowed him to see microscopic algae and protozoa and larger bacteria. He clearly had excellent eyesight because he accurately drew pictures of microbes that were at the limit of the magnification of his lens. He used only SINGLE LENS and not the compound lens of the true microscopes we employ today; which makes his observations all the more amazing. He wrote of his observations to the Royal Society of London in 1676 and included numerous drawings. He astonished everyone by claiming that many of the tiny things he saw with his lens were ALIVE because he saw them swimming purposefully about. This caused no end of shock and wonderment and numerous people hurried to Delft to see if this Dutchman was "in his cups" or if he was really onto something new and wonderful. A few minutes with one of his numerous microscopes was all it took to convert his visitors to enthusiastic believers in the existence of these tiny beasties living all around them. His discovery was the equivalent of our finding life on Mars today. For more information visit this site.
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Figure 2. A copy of Leeuwenhoek's microscope. Since his scopes were made of gold and silver his family sold them after he died. This copy was made from descriptions of his microscopes. The specimens were placed on the point and adjusted so they lay in front of the tiny lens. The specimen was placed so that a beam of sunlight passed through it and the viewer looked through the tiny lens at the illuminated material. Compare this with your laboratory scope. |
Robert Hooke was the first person to propose the CELLULAR forms of life. Visit this site and view Hooke's microscope. Another great site for learning about all kinds of microscopes is here.
In the first two laboratory exercises you
will be learning to use the microscope. When you use the 40X high dry lens to view the
various pond water samples you will be seeing the microbial world much as Leeuwenhoek did
(40 x 10 = 400X). Imagine the reactions of Leeuwenhoek's friends and family when he told
them of the wonders he had seen. Would you have the strength of character to withstand the
derisive comments and to continue your investigations had you been him? Scientists who
present new perspectives and data that fly in the face of conventional wisdom often face
ridicule and derision from their fellow scientists and the community at large. Ask your
associates/friends what they think of "global warming" and the "hole in the
ozone" and the scientists that propose these theories.
Many scientists and trendy high society people visited him to view his "little animalcules". including the Czar of Russia and other European royalty. He treated everyone the same and refused to even let them touch his scopes, rather he would prepare a sample and allow the visitor to come in and look briefly through the lens. He was a superior observer and an excellent scientist except for the CRUCIAL FLAW of not allowing others to copy his techniques and VERIFY his results. Because of this and the failure of people to relate these tiny microbes with disease, it was another 200 years before the science of Microbiology really took off.
Can you think of cases where people you know don't accept information that will aid them in living healthier, and longer lives? |
In the 1800s people (mainly the poor) began to use hospitals. Hospitals also became centers of physician training. In 1841 (30 years before the GERM THEORY of disease was established) young doctor IGNAZ SEMMELWEIS was hired to run a maternity ward in a Vienna hospital. There were two birthing wards in his preview, one run by midwives and the other by doctors. Semmelweiss noticed that the death rate among mothers in the doctor's ward ran as high as 18% from the blood infection (of a #streptococcus or STREP) known as CHILD BED FEVER or PUERPERAL SEPSIS, whereas in the midwife ward the death rate was much lower. When he suggested that the doctors might contribute to this he was fired. Subsequently rehired, he saw a friend die from PUERPERAL SEPSIS after cutting himself during an autopsy of a patient who had died of PUERPERAL SEPSIS. He reasoned that there was an INVISIBLE AGENT that caused both deaths and that one could transfer it from the autopsy room to the birthing rooms and thus infect the mothers during birthing. Acting on this assumption, Semmelweis instituted sanitary measures which included having the doctors wash their hands in disinfectant and change from lab coats dripping with pus and blood from the autopsy room to clean lab coats before examining patients or assisting in a birth. The death rate of the mothers dropped by 2/3 in his ward. However, the other doctors objected so strongly to his rules that Semmelweis was again fired and left Vienna. He took other hospital jobs where he instituted the same standards of cleanliness which resulted in the same decline in deaths and a revolt of his fellow physicians. Semmelweis ended up dying in an insane asylum from a blood infect that resembled puerperal sepsis (bacterial revenge?). COULD SOMETHING LIKE THIS HAPPEN TODAY in the treatment of disease?
The mystery of life has puzzled and confounded humans since the first human began to contemplate his world. The religions of ancient societies were built around the seasons, the sun and the renewal of life as these were so clearly tied to survival; both of the human species through birth and death, and of the individual in the attainment of sustenance (#ENERGY). SPONTANEOUS GENERATION or the idea that life routinely arises from non-life was a COMMON SENSE explanation of the miracle of life. It had the advantage of simplicity, ease of understanding and didn't require any waste-of-time thinking. As science and the scientific method grew with the slow accumulation of knowledge, observant individuals began to consider the origin of life more deeply. Simple observations convinced many people that all the larger animals and plants produced life from previous life. Despite this, the mass of humans clung to the comfortable idea of SPONTANEOUS GENERATION Further, religions saw it as a convenient way to demonstrate the hand of God operating continuously in the WORLD. Some individuals, such as J.B. van Helment even described how one could make mice from grain, a jar and dirty rags by putting them together in a dark place for a few weeks and soon mice would appear in the jar. Other, more perceptive individuals, like F. Redi tested the common idea that maggots arise via SPONTANEOUS GENERATION on rotting meat. He placed a piece of meat in three jars, one he left open, one he corked tightly and the third he covered with a fine mesh gauze. Maggots only appeared in the open container, no matter how long he left the jars.
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Redi's experiment was important because of its eloquent simplicity. Anyone could repeat it and obtain the same clear results. Nevertheless, many people clung fiercely to the idea of SPONTANEOUS GENERATION, while others designed experiments to test it. In every case the results of the majority of these experiments indicated that SPONTANEOUS GENERATION did not occur. The intellectual ferment this controversy stirred up gradually evolved into the #SCIENTIFIC METHOD as the various antagonists questioned each other's assumptions and, more importantly, their experimental design. These arguments forced the designing of BETTER EXPERIMENTS (with good #CONTROLS) and eventually persuaded all but the most recalcitrant believers to discard SPONTANEOUS GENERATION as an explanation for all higher life forms. Then, in the 1800's the refinement of the microscope, through which people could see tiny life forms that they assumed were SIMPLE, gave SPONTANEOUS GENERATION proponents new life.
Again, flawed COMMON SENSE led reasonable people astray. As the existence of microscopic life was accepted, the assumption was that such life must be SIMPLE compared to higher, more COMPLEX life. The reasoning that followed this erroneous assumption was that since the microbes were small they must be simple & it followed that they were formed by SPONTANEOUS GENERATION, hence God was still at work creating micro-life. As we shall see in later discussions, small is not simple! The battle over SPONTANEOUS GENERATION raged anew both from the pulpit and the lab. A number of scientists performed elementary experiments in which they treated soups and broth's, which left unheated would team with microbes after a few days, with heat to destroy any life present in them and asked the question: "Would new life arise in these sterile soups"? Spallanzani boiled "soup" in glass containers and melted the glass closed. The observation that nothing subsequently grew in this "heated" soup suggested that SPONTANEOUS GENERATION didn't work. His detractors, rightly criticized his experiments, proposing that since air is necessary for life and since he had sealed the flask to air, obviously NO LIFE could develop. Others boiled soups and microbes grew, thus apparently supporting SPONTANEOUS GENERATION. But again the preponderance of data suggested that SPONTANEOUS GENERATION did not even apply to the "simple" microbes.
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In 1859 one of the fathers of modern microbiology, L. Pasteur (picture and short biography) decided to settle the question of SPONTANEOUS GENERATION once and for all. A genius at devising definitive experiments, Pasteur first drew the necks of glass flasks out so that they remained open to the air, but were bent so that air could only enter by a curved path. He then added broth and boiled it to destroy contaminating microbes. These flasks were then incubated and observed for months. He reasoned that the microbes in the air that could contaminate the sterile broth would be trapped on the sides of the thin glass necks before they reached the sterile broth. If SPONTANEOUS GENERATION didn't occur no growth should take place. This is exactly what happened, the flasks remained sterile indefinitely, until Pasteur tipped the sterile broth up into the curved neck where he predicted the airborne organisms would have settled. After doing this the broths ALWAYS GREW MICROBES. These experiments ended the SPONTANEOUS GENERATION controversy because these experiment was so elegant and simple, and the results so clear, that anyone could repeat them.
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Later, an earlier problem, in which occasional heated-broths did not remain sterile, was explained with the discovery of the heat resistant bacterial #SPORES , some of which could can survive several hours of boiling without being killed.
Pasteur discovered many of the basic principles of microbiology and, along with R. Koch, laid the foundation for the science of microbiology. In 1857 Napoleon III was having trouble with his sailors mutinying because their wine was spoiling after only a few weeks at sea. Naturally Napoleon was distraught because his hopes for world conquest were being scuttled (pardon the pun) over a little spoiled wine, so he begged Pasteur for help. Pasteur, armed with his trusty microscope, accepted the challenge and soon recognized that by looking at the spoiled wines he could distinguish between the contaminants that caused the spoilage and even predict the taste of the wine solely from his microscopic observations. He then reasoned that if one were to heat the wine to a point where its flavor was unaffected, but the harmful microbes were killed it wouldn't spoil. As we are aware this process, today known as PASTEURIZATION, worked exactly the way he predicted and is the foundation of the modern treatment of bottled liquids to prevent their #spoilage. It is important to realize that pasteurization is NOT the same as sterilization. Pasteurization only kills organisms that may spoil the product, but it allows many microbes to survive, whereas STERILIZATION kills all the living organisms in the treated material.
Pasteur also realized that the yeast that was present in all the #wine produced the alcohol in wine. When he announced this, a number of famous scientists were enraged, because the current theory of wine production was that wine formation was the result of SPONTANEOUS chemical changes that occurred in the grape juice. Pasteur was attacked furiously at scientific meetings, to the point where certain scientists did humorous skits about Pasteur and his tiny little yeast "stills" turning out alcohol. Pasteur had the last laugh however as people all over the world soon realized that if he was right they could control the quality of wine by controlling the yeast that made it. In a short period many others verified his observations and the opposition sank without a sound.
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Pasteur also founded #MODERN IMMUNOLOGY when he realized that chickens became immune to a bacterial disease if injected with a "weakened" (avirulent) form of the pathogenic bacterium. While investigating chicken cholera, he injected some chickens with an old culture of the bacterial pathogen. When the chickens didn't die he realized that the culture was no longer pathogenic, perhaps because it had died, so he repeated the experiment with a fresh culture. Again he injected a number of chickens with lethal doses of a virulent culture, but only some chickens died. In questioning his technician about the source of the chickens, he learned that those chickens that didn't die when they were injected with the new, live, virulent culture were ones that had been previously injected with the "OLD, SICK" culture. For more information on Pasteur visit this site.
A case of the "Microbes Revenge": During his investigation on bacteria two of Pasteur's daughters and his father died of #Typhoid fever. |
In one of those flashes of genius that can change the course of history Pasteur realized that the OLD CULTURES had IMMUNIZED the chickens. He reasoned that under adverse conditions a virulent microbe may lose its ability to produce a disease but still retain its ability to immunize the exposed host. He went on to produce vaccines against a number of scourges including anthrax and rabies using this approach. Still today, most vaccines are made with a modification of this general technique. Only with the rise of molecular biology are we developing newer methods of vaccine production and #immunization. Lately it has been discovered that Pasteur didn't quite tell the whole truth about some of his data as he was under terrific pressure to show successful results. Do you think this is a problem in science today?
In the late 1870s a country physician, R. Koch became interested in anthrax, a common disease of both the farmers and their animals in his rural practice. Using a microscope purchased with his meager funds, Koch saw a large bacterium in the blood of anthrax victims. He reasoned that it might be the agent of the disease, but he knew that as a hick country doctor he would have difficulty getting such a controversial proposal accepted. Using a closet at home as his lab and developing basic microbiological techniques as he proceeded, Koch painstakingly teased out the anthrax bacterium and purified it. He then inoculated the purified bacteria into healthy animals and produced the classical clinical disease. When he examined the blood of the inoculated animals he was able to re-isolate the same bacterium. He repeated the isolation, infection and disease cycle until he was certain he had found the agent of anthrax. Because it was such an important commercial disease and because his techniques could be easily duplicated, others quickly verified his findings and Koch became famous. He soon had his own institute (like Pasteur) and other discoveries soon followed. Koch attracted other bright scientists and together they (along with Pasteur's group) developed the basic techniques of microbiology labs we still use today. These include the sterile culture techniques, pure culture techniques, the use of petri plates, inoculation needles, solid medium, the use of agar and gelatin to produce a solid surface, the Gram stain and other staining procedures. In addition Koch discovered the etiological agents of #cholera, and #tuberculosis. His studies, in combination of those of Pasteur's, established the GERM THEORY of disease. His procedure for defining the agent of any disease, called KOCH'S POSTULATES, consists of the following 4 steps.
FIRST, isolate the suspected agent from a disease victim.
SECOND, grow the agent in pure culture.
THIRD, infect a healthy host and show
that the organism produces the CLASSICAL CLINICAL
DISEASE.
FOURTH, ISOLATE the "same" organism from the new victim.
In general we still follow these dictates today (Visit this site). However, there are cases where it is not possible to do this. For example, many viral diseases of man (e.g. #HIV) do not infect other species, even our close primates, so it is not possible to carry out steps 3 and 4. In other case such as #syphilis, leprosy and the agent of #genital warts it has been difficult if not impossible to grow the organism as an isolated in vitro (= in the test tube) culture, which severely limits our ability to study the organism. For more on Koch visit this site.
MICROBIAL SERENDIPITY:
Until recently, few women have played a significant role in microbiology, however this
young science owes the development of a crucial
technique to a woman. Fanny Angelina Eilshemius was born in 1850
in New York of a wealthy Dutch immigrant family. As a young girl, Angelina toured Europe
where she met a young German doctor, Walther Hesse, whom she married in 1874. Angelina
Hesse settled down to being the wife of a busy country physician. W. Hesse, became
interested in the new science of Microbiology and joined Koch's lab in 1881. Dr. Hesse
studied many aspects of bacterial public health and bacterial metabolism . His wife,
nicknamed Lina, assisted him, much like my wife does me, as a laboratory technician. She
was a talented artist who drew illustrations for his publications. One hot summer when
Walther was attempting to do counts on bacterial air contaminates he was having trouble
with his GELATIN (what
we call Jell-O) plates
melting in the heat and being digested by many of the bacteria he tried to grow on them.
In frustration, he asked his wife "Why do
your jellies and puddings stay solid in the warm weather?".
She explained to him that she used AGAR-AGAR, a complex polysaccharide extracted from seaweed, to keep them solid in hot
weather. AGAR-AGAR had been used as a gelling
agent in ASIA for centuries. She had learned of it as a
youngster in New York from a Dutch neighbor who had immigrated from Java. Presumably Dr.
& Mrs. Hesse discussed the possibility of using agar-agar to prepare microbial media
and Dr. Hesse subsequently found that it worked beautifully. The following characteristics
of AGAR-AGAR make it almost perfect for the growth of microbes on solid medium:
This kitchen ingredient revolutionized the science of microbiology as it made what had been an arduous task of separating and growing microbes on solid surfaces a routine procedure. Dr. Hesse went on to make other important bacteriological discoveries and advances, such as bringing the pasteurization of milk to Germany; which prevented the death of children from TB- and milk contaminated with intestinal pathogens. Angelina died in 1934, when I was one year old, so you see how NEW the science of microbiology is? Ref.: ASM News 58:425 (1992).
Smallpox was one of the greatest scourges of mankind. For thousands of years it swept through human populations, killing up to 40% of its victims and leaving many of the survivors horribly scarred for life; their faces covered with deep red pits. Because of the propensity of the male to appreciate females with healthy complexions, many a beautiful young woman became a pox-scarred spinster because no man would marry them. The ancient Chinese recognized that those who recovered from a case of "the pox" were IMMUNE to smallpox. Some unknown person in CHINA, perhaps noting that even people who only developed a few scabs were as immune as those whose bodies were covered with scars, took material from a dried scab and scratched it into an uninfected person in an attempt to IMMUNIZE them. It worked and the process was repeated by others, with the technique eventually reaching India. From India it traveled by various routes to Europe in the 17th century where it came into common usage. The only problem was that the scab from a victim contains fully #virulent virus capable of producing the clinical disease. Thus, while one person might have only a mild case and become immune, they shed the virulent virus and were capable of starting their own #epidemic. Whereas the next person inoculated with the same scab-material could just as easily develop a FULL BLOWN CASE and die in agony.
This was the situation when Edward Jenner entered the picture. Through a series of serendipitous events, Jenner was led to the discovery of immunization and to the eventual elimination of the scourge of smallpox from the earth. As a young man he had lived in the country and had been told by a milkmaid that "she never had to worry about catching smallpox because she had had "cowpox", a mild chronic disease of cows that milk-maids usually contracted as a rash on their hands. Later, after Jenner became a physician and took up a country practice, he remembered the milkmaid's story. He began asking questions and was told by local men that "if you want to marry a woman who will never be scarred by the 'POX', marry a milkmaid". By 1796 he became convinced that the story was true so he inoculated an 8-yr. old boy with cowpox and 8 weeks later inoculated the same boy with the pus from a smallpox lesion. The boy showed no effects and Jenner repeated the experiment. As word of his results spread, others began to test it and by 1803 it was an established medical procedure in England. Shortly thereafter Ben Franklin encouraged American doctors to adapt this technique in view of the dangers inherent in the older technique. For more on Jenner visit this site.
CRITICAL THINKING QUESTION: What do
you think of Jenner using a child to test his theory on? Do we experiment today on people
without their knowledge?
CRITICAL THINKING QUESTION: Today we
have eliminated (almost) smallpox on earth. The only two sources of the virus are in
special labs in the US and Russia. There is a debate among the scientific community as to
what to do with these remaining virus. In 1996 they were just hours away from being
destroyed when a decision was made to have more debate. What is your vote? There is some
question as to whether other, unreported, stocks of smallpox virus #still exists.
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Paul Ehrlich worked in Koch's lab where he learned to study bacteria. While considering the phenomenon of #differential staining of different bacteria and of different components of eukaryotic cells, he speculated that if a dye chemical could bind to one cell and not another or to one substance within a cell and not others, perhaps you could find chemicals that would selectively kill certain pathogens without harming the surrounding host cells; this would act like a MAGIC BULLET selectively killing the villain and sparing the innocent victim. He embarked on a search for a magic bullet to cure syphilis, which in the late 19th century was a scourge as terrible as AIDS is today. In the final stages of syphilis, a sexually transmitted disease or #STD, its victim suffered horribly and eventually died insane as the brain was destroyed by the infection. Over many years he tested 100s of chemicals and finally in 1910 he found one, he named SALVARSAN or compound 606, that killed the syphilis organisms without killing the host (usually). This discovery laid the ground for the discovery of #antibiotics and other chemotherapeutic agents.
CRITICAL THINKING
QUESTION: Many of the clergy of Ehrlich's day opposed his attempts to find a cure for
syphilis because they said this was God's punishment for the sin
of fornication. Can you think of a parallel that applies today?
The major points to take away from this Chapter are:
The following are references relating to the history of Microbiology that you might find enjoyable reading:
History URLs:
Copyright © Dr. R. E. Hurlbert, 1999.
This material may be used for educational purposes only and may not be duplicated for
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