Introduction: (A painting of a plague-ravaged city to be shown here [8]) The Bubonic Plague devastated Europe in the 1300s, killing roughly one third of the population. Those who contracted the disease had a 75% chance of death (11). (A picture of a "Bubonic arm" shown here [5]) Doctors of that era suggested many ridiculous methods of curing the disease, including bathing in urine, placing dead animals in the home, drinking molten gold and powdered emeralds, eating figs before six in the morning, and chopping up a snake everyday (11). Now, doctors know that Black Death is really caused by the bacteria Yersinia pestis and is curable using antibiotics (11). Antibiotics are chemicals released by microorganisms to hinder the growth of other microorganisms and the focus of my speech today (6).
Central Idea: Antibiotics are arguably the most important substances known to our society.
Partition/Preview: The significance of antibiotics in our everyday lives can only be understood after a careful examination of their history, function, and uses.
Transition: As a college student, I must discuss the history of these drugs first.
I. All advancements in antibiotics have been made in the last one hundred years.
A. The discovery of the first antibiotic ranks among the greatest events in medical history.
1. Going through school, our science teachers have told us that Alexander Fleming discovered penicillin in 1928 - this is false.
2. Penicillin was actually discovered by a French medical student, Ernest Duchesne, in 1896, but the scientific community largely ignored Duchesne's work (4).
3. Fleming's work was recognized as the first scientific study of penicillin.
a. Fleming happened upon penicillin by accident when one of his Petri dishes was contaminated with the fungi, Penicillium notatum (4).
b. Unfortunately, Fleming found the substance to be unstable (and sometimes nonfunctional), so he stopped researching and published his last paper in 1931 (4).
B. War is a time for fighting disease.
1. In almost any war, infected wounds kill more people than the wounds alone.
2. In the late1930s England, scientists Howard Florey, Ernst Chain, and Norman Heatley "purified penicillin for testing in mice" (4).
a. Mice survived bacterial infections when treated with the antibiotic (4).
b. A successful human clinical trial took place in 1940 (4).
3. England could not manage the production of penicillin amidst World War II, so the entire industry was moved to the United States (3).
4. During World War II, penicillin was only administered to military personnel. -- John C. Brown, of the Science Museum of Minnesota, owes his life to antibiotics because his father was in the U.S. Army during this time (3).
C. Since the 1940s, dozens more antibiotics have been discovered and/or synthesized in laboratories worldwide.
Transition: Now that I've painted a good backdrop for the discussion of antibiotics, it's time to explore why their discovery was such a scientific breakthrough.
A. Some antibiotics inhibit cell growth irreversibly and are called bactericidal (2)&(12).
1. Penicillin and its derivatives (ampicillin and amoxicillin included) prevent the formation of the cell wall in new bacteria cells (12).
a. The cell wall is very important in maintaining the concentrations of nutrients in cells (12).
b. (A video clip showing the effect of penicillin on bacteria [7]) Without a cell wall, bacteria cells fill with chemicals but cannot divide; and when the cell can stretch no farther, the cell membrane ruptures (7).
c. Penicillin has two important limitations: it only stops the growth of new cells and is only effective on gram-positive bacteria (12).
2. Polymyxin and gramicidin are types of antibiotics that affect the cell membrane (12).
a. The cell membrane is very important in maintaining the internal osmotic pressure of cells (12).
b. Polymyxin accumulates on the surface of bacteria and disrupts the function of the cell membrane (12).
c. Polymyxins are also more active against gram-negative bacteria than gram-positive bacteria (12).
d. Unfortunately, these types of antibiotics are too toxic to be used medicinally (12).
B. Other antibiotics inhibit cell growth reversibly (by preventing bacteria from making copies of themselves) and are called bacteriostatic (2)&(12).
1. Antibiotics that affect protein synthesis and nucleic-acid metabolism fall into this category (12).
a. Erythromycin inhibits protein formation and is one of the best antibiotics available today (2).
b. Other bacteriostatic antibiotics can inhibit a cell's nucleic-acid metabolism by acting on the level DNA replication and transcription (i.e. anthracycline antibiotics) or the level of translation (i.e. streptomycin) (12).
2. Iron-containing antibiotics, sideromycins, affect the iron metabolism of cells by inhibiting the function of important metabolites, sideramines (12).
Transition: With such a wide array of antibiotics at our disposal, it is easy to see why our society utilizes them so extensively.
A. The number of medicinal uses is nearly limitless.
1. Antibiotics are used to cure a variety of common bacterial and fungal infections throughout our bodies, from eye infections (i.e. conjunctivitis) to urinary tract infections (i.e. cystitis) (10).
2. Thanks to antibiotics, many of the diseases that plagued our ancestors are now curable, including diphtheria, pneumonia, dysentery, cholera, tetanus, tuberculosis, leprosy, bacterial meningitis, and Bubonic plague :) (10).
3. Antibiotics are also very important for fighting off secondary bacterial infections that result when nonbacterial diseases leave immune systems weak (10).
a. Some examples of viral infections that can lead to secondary bacterial infections are bronchitis, the common cold, influenza, and a variety of sexually transmitted diseases (10).
b. An example of a non-viral, genetic disease that can lead to secondary bacterial infections is Cystic fibrosis (10).
4. It is estimated that 25 to 40 of hospital patients receive antibiotics intravenously (9).
5. Doctors write 150 million antibiotic prescriptions each year to people who are not hospitalized (9).
B. Antibiotics are just necessary in agriculture as they are in hospitals.
1. According to Stephen Sundlof, Director of the Center for Veterinary Medicine (CVM) at the Food and Drug Administration (FDA), antibiotics serve two purposes in animal agriculture: to better animals' growth rate and feed efficiency and to prevent and treat diseases among livestock (1).
2. "Stuart Levy, M.D., has estimated that of the 50 million pounds of antibiotics produced in the United States, over 40% are used...for farm animals and agricultural crops" (Nordenberg, 1998). According to Levy, 20% of this amount is used to treat individual sick animals; the rest is used to better feed efficiency, ward off disease among herds, and save crops from disease (9).
C. Products containing antibiotics can be found on the shelves of stores all across the world, from dishwashing detergents to sunscreen.
Transition: When you go home, look around and see how many antibacterial products you own. The search may be easier than you think.
Conclusion: Who would have guessed that an initially disregarded chemical - discovered by a med student, no less - would become so important to our everyday lives? Antibiotics have been saving lives for only 60 years, but due to their variety and abundance, it is impossible to predict just how many years they have preserved for humankind. I hope all of you realize how significant they are to your life. When you go to lunch today, realize that much of the food you will eat is there because of antibiotics. When you next see your family (perhaps this very weekend) realize that, without antibiotics, they might not be there to welcome you.
1.) "Antibiotics in Animals: An Interview with Stephen Sundlof, D.V.M., Ph.D." http://ificinfo.health.org/insight/antibiot.htm
This article is part of the International Food Information Council's (IFIC) official web site. The IFIC works to make scientific information about food safety, nutrition, and health accessible and easily understood. The article is taken from the November/December 1994 issue of the IFIC-sponsored magazine Food Insight.
2.) Antibiotics Kidsite. Copyright 1997. http://www.kasman.com/aaron/bio/tindex.html
Aaron Kasman, Alissa Levy and Paul Rakowski created this site to help children understand antibiotics and how they work. It's an interactive storybook about the adventures of Billy Banana and his dream to be an antibiotic. The site provides a great dictionary of words associated with antibiotics. Since it is designed for children, the information is somewhat basic and written in terms that those without a scientific background can understand.
3.) Brown, John C. What the Heck is an Antibiotic? Copyright 1995. http://falcon.cc.ukans.edu/~jbrown/antibiotic.html
John C. Brown is a faculty member in the microbiology department at the University of Kansas. This article provides a general understanding of the history and functions of antibiotics. The Science Learning Network (SLN) and the Science Museum of Minnesota sponsor Brown's work.
4.) Brown, John C. What the Heck is Penicillin? Copyright March 1996. http://falcon.cc.ukans.edu/~jbrown/penicillin.html
John C. Brown is a faculty member in the microbiology department at the University of Kansas. This article provides an in-depth look at the history, structure, function, and uses of penicillin. The Science Learning Network (SLN) and the Science Museum of Minnesota sponsor Brown's work.
5.) The Bubonic (and other forms of) Plague. http://www.angelfire.com/sc/plauge/
A person only known as Nick designed this web site. It provides some general information about the plague and some links to other plague resources. The only thing I took out of it was a picture of the arm of a person with Bubonic plague.
6.) Campbell, Neil A. Biology (fourth edition). The Benjamin/Cummings Publishing Company, Inc., Menlo Park, California, 1996. Pp. 501-504.
7.) Cells Alive! How Penicillin Kills Bacteria. Quills Graphics. http://www.cellsalive.com/
Cells Alive! features a wide variety of pictures and video clips highlighting the liveliness of cells and their functions. The particular page of interest to me featured background on penicillin and a video clip of penicillin destroying bacterial cells. Cells Alive! was recently endorsed in the September 1999 issue of Popular Science.
8.) Janis, Ely. Bubonic Plague. http://ponderosa-pine.uoregon.edu/students/Janis/menu.html
Ely Janis is a student at the University of Oregon. The web site is filled with useful information about the disease. I believe it may even have been thesis research or something of the like. The painting used in my speech is from Janis's site.
9.) Nordenberg, Tamar. Miracle Drugs vs. Superbugs - Preserving the Usefulness of Antibiotics. http://www.parenthoodweb.com/articles/phw894.htm
This article was featured on Parenthood Web, a site that aims to provide parents and prospective parents all the information they need to make the best decisions for their children. The article was taken from the November-December 1998 issue of FDA Consumer Magazine.
10.) O'Grady, Francis, et al. (eds.). Antibiotic and Chemotherapy: Anti-infective agents and their use in therapy (seventh edition). Churchill Livingstone, New York, New York, 1997. Pp. 674-929.
11.) Parmley, J. Bubonic Plague or "Black Death." http://www2.educ.ksu.edu/Faculty/ParmleyJ/BlockOnePDS/Team6F97/bubonicplague.html
J. Parmley is a faculty member in the College of Education at Kansas State University. The web site features some very useful information about the Bubonic plague. The site itself appears to be a lecture.
12.) Zahner, Hans. Biology of Antibiotics. Springer-Verlag New York, Inc., New York, New York, 1972. Pp. 62-96. 3