PHC6562 Lecture1 Part1
Slide 1: Slide 1 Welcome to the first lecture for the Microbiology For Healthcare Workers course. The lectures for this course will be numbered in sequence as presented throughout the semester. The first lecture is labeled Lecture 1. Lecture 1 will be divided into Parts 1 and 2 for convenience; this is an effort on my part to avoid long presentations. Most, but not all of the lectures in this course will be divided into 2 parts. The formal course number is PHC6562.
As described in the introductory lecture, this course is divided into 2 modules. The first module comprises of lecture material that covers the basic concepts of microbiology and infectious diseases. Lectures 1 through 6 make up Module 1. The second module covers applications of Microbiology in Public Health. Module 2 is comprised of Lectures 7 through 12.
As an instructor for this course, I encourage questions being asked on material that may not have been clearly presented in the lectures. Since this is a web-based course, I encourage that questions be posted on the discussion board. This will enable other students to view the questions, as well as view Instructor and TA responses to the questions. However, if there is a need to contact instructors or the TA regarding course material or other matter, please do not hesitate do send out emails to us as needed.
Slide 2: Lecture 1 Overview of Microbiology In Lecture 1, I will introduce you to the discipline of Microbiology. In Part 1, I will start with a basic introduction to Microbiology, and then provide a historical perspective on how this discipline evolved. In Part 2, I will introduce you to groups of microorganisms, which are the main players in the field of Microbiology. Next, I will discuss the history of the microscope, from the historical perspective, to the description of the current modern types of microscopes that are routinely being used in diagnostic and research microbiology laboratories. I will end part 2 lecture 1 with a preview of some of the concepts that are covered in Chapters 1 and 3 of the assigned text book, Microbiology: A system's Approach.
Slide 3: Microbiology The question posed on this slide is, how does one define Microbiology? “Biology” can be defined as the study of life, and “micro” represents the study of microorganisms. These are organisms that cannot be viewed by the unaided eye, and can only be seen through the microscope. There are endless scopes, disciplines and applications of microbiology, which are described in detail in Chapter 1 of the assigned text book. The various disciplines of Microbiology correspond mostly to the types of microorganism under study. For instance, virology is the study of viruses, bacteriology is the study of bacterial pathogens, mycology is the study of fungal organisms, and parasitology is the study of parasites and the diseases they cause. The applications of microbiology are boundless. For instance, in the diagnosis of infectious diseases, the tools of microbiology are being utilized in the laboratory to detect the presence of the pathogen that cause the disease. This laboratory diagnosis confirms the diagnosis for the physician or other healthcare workers requesting specific diagnostic tests to detect the presence of the suspected organism, or pathogen. Microorganisms such as the bacterium Escherichia coli, or E. coli, are also used widely in the research field and industry for the production of useful or important biological products such as vaccines and recombinant proteins. Our world is filled with microorganisms- they are everywhere in our environment and living with us in and on our bodies. Pathogens are microorganisms that can cause infectious diseases. Only 3% of microorganisms can actually cause these specific infectious diseases by virtue of them being ‘infectious”. However, there is another category of microorganism termed “opportunistic pathogens”. These microorganisms normally do not make a person sick and can live harmoniously on our bodies as “commensals”. However, if the situation changes for the host, such as for hosts that become immunocompromised, or if these opportunistic pathogens find their way on persons of extreme ages, for instance (the very young or the very old), these same commensal microbes can become pathogenic and cause infectious diseases. There are also many microorganisms such as some specialized yeasts that we will discuss later in this lecture, that can be beneficial in food and beverage industries.
Slide 4: Slide 4 This slide shows the relative sizes of various objects, and the detection devices used to visualize them. The power of the eye, the most basic image sensor, has its limits. Anything smaller than the width of a single human hair cannot be seen with the naked eye. When the light microscope was developed in the later 1600’s, a whole new world of tiny wonders was discovered. The basic light microscope allows us to visualize objects such as the different types of cells such as bacteria, as well many other types of cells. The invention of the microscope opened up a whole new world. From the knowledge that microorganisms exist all around us, the field of microbiology was born. The electron microscope was invented in the mid-twentieth century. This instrument made it possible to detect even smaller objects that cannot be seen using a light microscope. This includes smaller molecules and viruses. The detection power of most electron microscopes stops just short of being able to visualize incredibly small structures such as the electron orbital systems of individual atoms. Atoms are considered the smallest units of an element that have the characteristics of that element. Similarly, cells are the smallest units of an organism capable of functioning independently. In Lecture 1 this course, we will learn about the different types of biological cells and the different classification of microorganisms that exist all around us.
Slide 5: Slide 5 In this slide, I am illustrating again the point I made earlier about the different types of microorganisms that are found all around us. Only 3% of all microorganisms are pathogenic, and 10% are opportunistic pathogens.
Slide 6: Beneficial Microorganisms There are many microorganisms that are utilized in various industries to prepare processed food and drinks such as bread, yogurt, wine, and beer. This slide lists the different ways these microorganisms become beneficial to us the consumers. Since ancient times, societies all over the world learned different ways to harness microbes for beneficial aspects, even before they knew microorganisms even exist!
Microbes in the environment participate in the cycle of life in the ecosystem, mostly as decomposers, and thus function as “recyclers”. An example is bacterial actions on decomposing materials in swampy areas, and as a result, we can detect the odor of “marsh gas” or methane in these areas. Microbes involved as scavengers are usually non-pathogenic and free-living. Microbes in the environment are also involved in the process of recycling of carbon, nitrogen, sulfur, iron and phosphorus, resulting in the return of these elements to nature for reuse.
There are many types of foods and beverages that are dependent on microorganisms for their production. The list is long and includes cheese, bread, many types of dairy products, wine, beer and many other types of drinks. Microbes have been utilized in the production of fermented foods for thousands of years. Fermentation is the process involving a series of chemical reactions, mediated by bacterial enzymes. During fermentation, sugars in the original food are broken down into acids or alcohol, and carbon dioxide. Which organism used during this process determines the taste and aroma of the product. For example, yeasts are fungi that are efficient fermenters of sugar into alcohol and carbon dioxide. This property of yeast is exploited in the production of breads and alcoholic beverages. The yeast strain Saccharomyces cerevisiae, known as “bakers yeast”, is commonly used for this purpose. Carbon dioxide produced by this yeast strain allows dough to rise, and is used to bake bread. Yogurt and other dairy products such as cheese is another example of popular food that requires microbes for production. Yogurt is fermented milk that is preserved by its acidity, and contains live bacterial cultures of predominantly Lactobacilli species, (which is mainly Lactobacillus acidophilus species). Decreased pH in yogurt causes milk to thicken and inhibit growth of pathogens. Foods supplemented with live microbes are called “probiotics”. Advocates of probiotics claim that there are many health benefits to consumption, which include partial replacement of normal flora for individuals on antibiotic therapy, reduction of blood pressure, regression of tumors as well as decreased diarrhea and gas production. Beer is brewed from barley, hops and water, and uses yeast to produce the alcohol during fermentation. Wine is fermented grape juice, that uses yeast (Saccharomyces ellipsoidues) to produce alcohol and carbon dioxide. Yeast extract, which is prepared from autolysing yeasts (separated using specialized centrifuges such as shown in the middle figure at the bottom of this slide) can be purchased for home use, such as for baking. Please do not worry about memorizing the specific names of beneficial bacteria and yeasts I just mentioned here. These names will not be asked on the exam pertaining to Lecture 1.
Slide 7: Slide 7 Microbes are also used as research tools. Genetics and molecular biology fields have benefited greatly from experimentations using different types of microorganisms such as bacteria and viruses. Biologists have capitalized on the fact that microorganisms are easy and inexpensive to grow, and reproduce rapidly. A very important bacterial species commonly utilized in the cloning of many important gene products for use in medicine and research is the gram-negative bacterium Escherichia coli. From information gathered through research, the beneficial microbes are harnessed in various industries to manufacture their metabolic products. Here, these products are usually produced in bulk. Examples of microbial products used in medicine include various proteins cloned and expressed in E. coli such as insulin and human growth hormones. There are some microorganisms that are harnessed for bioremediation. An example is the use of bioremediation to clean-up a major Exxon Valdez oil spill in 1989 off the coast of Alaska. Bioremediation is an emerging technology based on enzymatic capacity of microbes to digest or degrade a variety of material such as oil, paper, concrete, and textile. In the case of the Exxon Valdez oil-clean up, bacterial species utilized the oil as a source of nutrients, and replaced the oil as the bacterial population increased. In summary, I have discussed extensively the positive aspects of our associations with the microbial world. In subsequent discussions, we will concentrate more on microorganisms that cause infectious diseases, or pathogens, which is the focus of this course. Particularly, we will discuss the impact of these pathogens on the fields associated with Public Health in general.
Slide 8: Slide 8 Pathogens are a group of microorganisms that cause us to become ill. Pathogens can cause infectious diseases in humans, animals as well as plants. Human pathogens can be any one type of microorganism- bacteria, viruses, fungi, protozoa or prions. I would like to emphasize again that only 3% of all microorganism are pathogenic, and 10% are opportunistic pathogens.
Slide 9: Slide 9 This pie chart summarizes the most common types of infectious diseases in 2005 in persons of all ages. Acute respiratory infections such as pneumonia and influenza are the most common leading infectious disease killers. This is followed by individuals afflicted with AIDS (acquired immune deficiency syndrome), caused by the HIV virus, then diarrheal diseases, tuberculosis (TB), malaria, measles and hepatitis B and other infectious diseases.
I will describe in detail the different categories of microorganisms and the specific pathogens and infectious diseases they cause in subsequent lectures.
Slide 10: Microbiology: Historical Perspectives on Pathogens I will now switch gears and talk about the how the field of microbiology evolved through history. There is much we can all learn from studying how this very important field of study came about into history, from the early 17 th century to the present time. This will give us insights into the role of the microbiology discipline in Public Health. This understanding can assist us, the Public Health professionals, as we continue the struggle to control and eradicate various infectious diseases afflicting mankind.
People in ancient times used to believe in the theory of spontaneous generation. The belief was that life came from non-living matter or decaying organic matter. As early as the 16th century, ideas began to form suggesting there might be invisible organisms that are able to cause diseases. In 1665, Robert Hooke introduced the idea of existence of cells. A century later, disputes about the theory of spontaneous generation began to emerge, and the theory was finally disproved in 1861 by experiments performed by Louis Pasteur. There were many important timelines from the 17th through the 20th century, particularly in the 19th century where the field of Microbiology expanded rapidly. An important event at the turn of the 19th century is the introduction of the first safe vaccine by Edward Jenner in 1796. Another revolutionary finding at the time was the realization of the importance of handwashing in prevention of infectious diseases in hospitals. This was introduced by Ignaz Semmelweis in 1847. Florence Nightingale devoted her life to promoting cleanliness and ventilation in health-care institutions, which also took place in the 19th century. There were many important early contributors to the field of microbiology that saw to its rapid growth and expansion. In the next few slides, I would like to highlight significant findings and ideas introduced by these individuals.
Slide 11: Major Contributors to Microbiology Prior to 1900’s This slide lists the names of major contributors to the field of microbiology, prior to the 1900’s. The work of these individuals as well as some others will be discussed in more detail in subsequent slides. You would have noticed by now that I listed many dates of historical events on various slides. However, I do not expect for you to memorize the specific dates, but please keep in mind the approximate time within a specific century the highlighted events occur. Anthony van Leeuwenhoek invented a better microscope in 1685 but was not the first person to invent the microscope. The first compound microscope was invented in 1590 by Hans and Zacharias Janssen, and this design is still used today as the dissecting microscope. Robert Hooke invented the first single lens microscope, and was the first person to report seeing what appeared to be “microbes” through the microscope. Leeuwenhoek who invented better microscope was the first person to see red blood cells and protists, and gained fame from his reports regarding his observations. Louis Pasteur made many important contributions that moved the field of microbiology forward at a rapid pace. He introduced the idea of fermentation when he showed that yeast can break down sugar into alcohol and carbon dioxide while also able to multiply in the process. Pasteur also disproved the theory of spontaneous generation through several experiments, the most convincing of which is the one using the swan necked flasks. He then proposed the idea of the germ theory of disease. Louis Pasteur also introduced the process called “pasteurization” that is now widely utilized to preserve beverages. Vaccines for anthrax, chicken cholera and rabies were also developed and introduced by Pasteur. Joseph Lister is well know for his contributions to control of infectious diseases in hospitals, by his introduction to the concept of aseptic technique. Robert Koch who built on Pasteur’s germ theory of disease was the first person to cultivate anthrax outside the human body. A protocol based on this finding known as “Koch’s Postulate” was developed as the gold standard, which is still used today to identify the etiological agent for an infectious disease. Robert Koch received the Nobel Prize in 1905 for proving the cause of tuberculosis.
In the next few slides, I will present these findings in greater detail as I believe it is important for us to have a thorough understanding of how the science of microbiology was conceived and evolved through time.
Slide 12: Anthony van Leeuwenhoek 1685 As mentioned in the last slide, Anthony van Leeuwenhoek invented a better microscope that allowed him to visualize many tiny microorganisms. He named these organisms “animalcules”, which we know today to be algae, protozoa and large bacteria. The single lens microscope he used is shown here on this slide. He originally was a cloth merchant in Holland who had the idea of inventing the microscope after using magnifying glasses to view the quality of weave while he was in England. He developed lens grinding to an art and meticulously developed lenses from gold and silver. His best lens was able to magnify between 300 to 500 fold, which then enabled him to visualize the “animalcules”.
To use his lens, specimens were placed on the point and adjusted so they lay in front of the tiny lens. The specimens were then placed so that a beam of sunlight can pass through it. Viewers can then look through the lens at the illuminated material for visualization.
He was a natural born scientist in that he reported his findings by writing to the Royal Society of London in 1676, and included many drawings to illustrate what he observed. He made the claim that these little creatures were alive, which shocked the whole society at the time. His finding was real significant, and would be equivalent if we were to find life on Mars today.
Slide 13: Edward Jenner, 1796 I mentioned that Louis Pasteur made a significant and revolutionary contribution to the field of microbial immunity by introducing vaccines against anthrax, chicken cholera and rabies. However, Edward Jenner is credited with inventing the first vaccine for small pox in the late 1700s. In 1796, Jenner, a British Physician, developed a controversial experiment to test his theory that led to the smallpox vaccine. He speculated that an individual who became infected with cowpox could be protected against the more virulent smallpox disease. This idea came about from the circulating rumor at the time which villagers often recanted; ie “if you want to marry a woman who will never be scarred by the pox, marry a milkmaid”.
To test his hypothesis, Edward Jenner created inoculation with scrapings from cowpox lesions from a young milkmaid named Sarah Nelmes, and then injected it into an 8 yo boy named James Phipps. As expected, James developed a mild fever and cowpox lesions. After a few weeks of recovery, Jenner injected James with the live small pox virus and found that indeed the boy was protected from small pox disease. The event is depicted in the drawing on this slide.
In 1798, Edward Jenner published his finding and presented them to the Royal Society of London.
Slide 14: Pasteur, 1855-1890’s disproves spontaneous generation I have mentioned the theory of spontaneous generation a few times in previous slide, and how Louis Pasteur finally disproved this theory once and for all, using a simple yet elegant experiment using swan necked-flasks. The experiment is illustrated in the drawing on this slide.
In ancient times, people used to believe that maggots were produced from rotting meat, or that rotting food could produce living organisms. This was too simplistic an idea but was widely accepted until first challenged by a scientist named Redi. He designed a simple experiment which proved that maggots were not spontaneously produced in rotten meat.
Louis Pasteur, whom many consider to be the “father of modern microbiology” decided to disprove this theory of spontaneous generation once and for all, by designing the simple experiment that was very convincing. He designed a curved-neck flask as shown on this slide so that the contents in the flask remained open to air, but were bent so that air could only enter through the curved path. He then added broth and boiled the broth to kill contaminating microbes. He reasoned that microbes that could contaminate the broth would be trapped on the side of the thin glass neck, and would not contaminate the broth.
If spontaneous generation didn’t occur, no growth would take place in the broth, and this was exactly what happened. Growth only occurred in the broth when Pasteur tipped the sterile broth up into the curved neck where he predicted the airborne organisms would have settled (depicted as the black dots in the drawing on the slide). After coming into contact with the contaminated neck, the broth would always grow microbes. This experiment ended the spontaneous generation theory because it was simple yet elegant, and is reproducible. Other experiments performed by Pasteur regarding microbial growth and swan-neck flasks are described in Chapter 1 of your book, in which his technique of breaking the neck of the flask to expose the liquid to dust and microorganisms showed similar results.
Slide 15: Louis Pasteur 1822-1895 Louis Pasteur discovered many of the basic principles of microbiology and, along with Robert Koch, laid the foundation for the science of microbiology. Pasteur was a chemist and a microbiologist who was the first to discover that putrefaction and fermentation were caused by microorganisms. In 1857, Napoleon III recruited Pasteur’s help to prevent spoilage of wine. After observing spoilt wine under the microscope, he reasoned this is caused by activities of microbes. He thought that wine heated to the point of killing the microbes but preserving the flavor, would prevent spoilage. This idea later proved to be true. From this, the process of “pasteurization” was introduced. Pasteurization is utilized today for preservation of many beverages, particularly for milk and other dairy products. However, pasteurization is not a complete sterilization process, since it does not kill all microbes.
Pasteur also discovered that it was the yeast present that produced alcohol in wine through the fermentation process.
Louis Pasteur also made a significant contribution to the field of vaccination and immunity. In studying chicken cholera, he found that attenuated organisms (ie microorganisms that have been weakened) inoculated into poultry offered protection against the virulent strains, and thus introduced the concept of vaccination. Pasteur also developed vaccines against anthrax and rabies.
In 1888, the Pasteur Institute was founded in Paris for the treatment of rabies, and he worked there until his death in 1895.
Slide 16: Slide 16 This slide summarizes the timeline of what I had described, about some of Pasteur’s contributions to the field of microbiology.
Slide 17: Joseph Lister 1827-1912 Joseph Lister, a British surgeon, contributed much to our understanding of the causes of diseases.
Lister introduced the concept of “antiseptics” into surgery which helped reduce infection of post-surgical wounds.
Joseph Lister was studying coagulation of blood in injuries and surgical wounds. This was when he noted a high incidence of infection in wounds, in spite of the efforts to keep rooms clean. To reduce the amount of bacteria in the environment, he tried spraying carbolic acid on surgical instruments and wound dressings. In 1860, it was noted that this effort reduced the mortality rate by 15%. Following this, this practice of using “antiseptic” was later accepted.
Slide 18: Robert Koch 1843-1910 Germ Theory of Disease 1876 Apart from Louis Pasteur, Robert Koch is another significant contributor to the young developing field of microbiology at the time. Like Pasteur, another Institute was also built to honor Koch. His work started from his early effort to build on Pasteur’s germ theory of disease.
Robert Koch received the Nobel Prize in Physiology and Medicine in 1905 for his investigations and discoveries in relation to tuberculosis.
Slide 19: Slide 19 Robert Koch was a German country physician who worked on diseases afflicting many farmers and their farm animals in rural areas.
In the late 1870s, he became interested in anthrax that afflicted these farmers and their animals. Through a microscope, he was able to visualize large bacteria in the blood of anthrax patients. He postulated that this was the agent that caused anthrax but knew at the time, he needed to provide convincing evidence to prove his theory. Therefore, he painstakingly teased out the anthrax bacterium and purified it. He then inoculated the purified bacteria into healthy animals and later observed symptoms of anthrax disease developing in these animals. When he examined the blood, he was able to re-isolate the same organism. This protocol was reproducible in generating the disease and recovering the agent. Therefore, this protocol provided convincing evidence that anthrax was caused by this particular bacterium.
This approach has been named “Koch’s postulate” and is being used to the present time to determine the etiological agent of an infectious disease. In combination with those of Pasteur’s, Koch established the germ theory of disease.
Koch soon had his own Institute. Together with many young scientists, the basic techniques used in Microbiology labs were established at his Institute. This included sterile culture techniques, the use of petri plates, pure culture techniques, the use of agar in culture, Gram staining and other staining procedures. Some of these techniques will be discussed in lecturers to follow in this course.
Using Koch’s postulate and the many established techniques, Koch discovered the etiological agent for cholera and tuberculosis. He received the Nobel Prize for proving the cause of tuberculosis.
Slide 20: Slide 20 The steps involved in performing the Koch’s postulate are illustrated in this diagram, and will be summarized in detail in the next slide.
Steps Isolate potential pathogen Prepare pure culture Produce classical disease in an animal model Reisolate the pathogen from this diseased animal.
Slide 21: Koch’s Postulate The Koch’s postulate is summarized in this slide.
Slide 22: Further Development There were many historical events that took place that moved the field of microbiology forward at a very rapid pace. Some of the discoveries are listed on this slide, which include contributions by Paul Ehrlick in finding the cure for syphilis, as well the important work by Fleming which led to the discovery of the first antibiotic penicillin. Some of these had been discussed and some others will be presented in the next few slides. Next, I will talk about the revolutionary discovery of viruses and ways to cultivate them in tissues culture in the 1950s.
To summarize to this point, I would like to emphasize again that Louis Pasteur discovered many of the basic principles of microbiology, and along with Robert Koch, laid the foundation for the basic science of microbiology.
Slide 23: Micro timeline…others On this slide, I would like to step back into history and discuss a very significant contribution by a Hungarian Physician named Ignaz Semmelweis. He was a Physician whom, when performing autopsies between deliveries of babies, noticed that the mortality rate associated with deliveries was very high. This condition used to be called “Childbed fevers”. Semmelweis hypothesized that childbed fever was a contagious disease spread by doctors not washing their hands after performing autopsies prior to delivering babies. He experimented with washing hands using lime water before performing deliveries, and as a result the mortality rate in his ward decreased from 18.3% to 1.3%. This was indeed a significant finding which has revolutionized hospital infection control to this day. Hand washing is currently recognized to be the single most important practice in the prevention of communicable diseases.
Slide 24: Paul Ehrlick 1854-1915 Differential staining
Paul Ehrlick is credited for his findings that led to discovering the cure for syphilis.
The idea for finding the cure came to Ehrlick from his observation of a concept he called the “magic bullet”. He observed that differential staining of cells by certain dyes worked because the dye only binds selectively to specific cell components (as depicted in the illustration on this slide). He then reasoned that there would be chemicals that can selectively kill specific pathogens without killing host cells. Based on this hypothesis, he started to screen hundreds of compounds to find the cure for syphilis. At the time in the late 19th century, epidemics of syphilis were happening at an alarming rate and is reminiscent of the HIV/AIDS epidemic of today. In 1910, he found that the six hundred and sixth compound he screened had inhibitory properties against the syphilis agent, and called this “compound 606”. This compound was also given the name “salvarsan”. This was a significant discovery as it laid the foundation for chemotherapeutic agents.
Prior to this time in 1890, Ehrlick had already proposed a very important theory that antibodies are responsible for immunity in the fight against infectious diseases.
Slide 25: Ivanovski virus discovery(Tobacco Mosaic Virus) 1886 I would like to now introduce some background regarding the discovery of viruses as another group of microorganisms. We will discuss viruses in greater detail in subsequent slides.
In 1886, a Russian scientist Dmitri Ivanovski, showed that a plant disease that caused spots on leaves (please see the picture of tobacco leaves on the slide) called tobacco mosaic diseases, is caused by a kind of infectious agent that is filterable and smaller than the typical microorganisms ever described. Six years later, this theory was proven to be right based on the work by a Dutch scientist, Beijerinck, who recognized the virus that cause the disease on these tobacco leaves. He showed that far smaller than any known life form, this agent could be diluted many times in solution and still cause disease in the leaves. Interestingly, unlike bacteria, this life form could only reproduce by infecting tobacco leaves. The agent, or organism which is named “tobacco mosaic virus”, was the first virus ever recognized.
The first animal virus isolated was identified in 1898 to be the etiological agent for foot and mouth disease. The first human virus identified in the year 1900 was the agent that causes yellow fever.
It was not until the 1930’s that these viruses could be visualized, after electron microscopy was introduced. Most viruses are smaller than the wavelength of visible light. With electron microscopes, it was possible to increase magnification up to around 300,000 times the actual diameter, making it possible to see viruses for the first time.
Slide 26: Alexander Fleming 1881-1955 Perhaps the most well-known scientist concerning drug discovery is Alexander Fleming, a Scottish medical doctor who discovered penicillin. In recognition for his contribution, Fleming was knighted in 1944, which gave him the title “Sir Alexander Fleming”. Together with two other scientists, he was awarded the Nobel Prize in 1945, for his discovery of penicillin.
The history behind the discovery is quite fascinating. Fleming was one of the few surgeons working in London who administered salvarsan, or compound 606, introduced by Ehrlick, for treatment for syphilis. As a result, his practice grew to be very busy and he was given the nickname “Private 606”. Based on the success of salvarsan, Fleming had the idea that there would be other compounds that could be used to fight microbial infection in wounds that afflict soldiers during the war. When World War I broke out, most of the bacteriology lab staff went to France to set up battlefield hospital labs. Fleming made many innovations in treatment of the wounded, but none of the discoveries compare to his discovery of penicillin.
Fleming’s discovery of penicillin was somewhat “accidental”. In 1928, as he was straightening out a pile of petri dishes in the sink where he was growing bacteria, he noticed one dish in particular that was somewhat peculiar. He noticed that some mold was growing in this dish, which was not unusual. What was unusual was that the Staph bacteria all around the mold had been killed. He found out that the mold was the species called Penicillium notatum. Fleming presented his finding in 1928, which, at the time raised little interest. He published a report on potential uses of penicillin in the British Journal of Experimental Pathology. It took World War 2 to revitalize interest in penicillin, and Howard Florey and Ernst Chain picked up the work.
Collectively, this work on penicillin was recognized when Fleming, Chain and Florey were awarded the Nobel Prize in 1945.
Slide 27: Slide 27 This is the end of part 1 on lecture 1.
I hope the brief history of how the microbiology discipline evolved gave you a glimpse of what happened in the past to get to where we are today. We do owe much to the early pioneers who paved the way and changed how society lives to this day. Since the beginning of time, the field of microbiology has grown as we go through many pandemic diseases that force us to move at a rapid pace, in order to keep the rate of morbidity and mortality from infectious diseases at a manageable pace. In the mid-20th century, the Health Care professionals thought that the war against infectious agents had been won at the time, and particularly after the success of eradicating small pox. However, since then we have faced many other unexpected epidemics of various infectious diseases. Though some battles have been won, many more are still here and there are more come. The Public Health field that is involved in the control of infectious diseases has much work ahead yet to be accomplished.
I will begin Part 2 of lecture 1, with a brief introduction to the different types of microorganisms, or microbes, found in the microbial world.