David discovers the importance of using antibiotics correctly.
Segment length: 7:45
- How do antibiotics kill bacteria?
- What could cause an antibiotic to lose its effectiveness in curing a disease?
Chances are you or somebody you know had a sore throat recently. Most sore
throats are caused by viral infections. But some are caused by bacteria like streptococci.On
occasion, sore throats caused by streptococci can lead to rheumatic fever, an illness
which can cause pain in the joints and severe damage to heart valves.
When examining a patient with a sore throat, a doctor does a throat culture to see if
streptococcus is the responsible germ. This is done by wiping a cotton swab on the
patient's throat and sending the sample to a laboratory. With the lab test results,
the doctor can identify the causative germ and, if it is a bacterium, decide which
antibiotic should be prescribed to help kill it.
Antibiotics, once considered miracle drugs, have sadly been losing ground in the fight
against the same disease-causing bacteria that they routinely vanquished in the past.
Because bacteria grow rapidly, a single cell can potentially produce millions of new
cells each day. As they divide and reproduce, these cells have a natural tendency to
change or mutate. Since the 1950s, due in part to the improper use of antibiotics,
mutations have led to bacteria developing traits that make them more resistant to
antibiotics and thus more of a threat to public health.
Through a complex process that involves the exchange of genetic information, some
bacteria can even pass resistance along to unrelated strains of bacteria. As people
travel around the world they can spread resistant bacteria to other areas, further
magnifying the extent of the problem.
Antibiotics kill bacteria or arrest bacterial growth in a number of ways. Some, such
as the quinolones and Rifampin, attack bacteria by interfering with their ability to
divide. Others, such as the tetracyclines or aminoglycosides, prevent the manufacture
of certain proteins essential to the bacteria. Penicillin antibiotics attack the
ability of the bacterium to construct its cell wall. Through mutation, however,
certain bacteria have acquired the ability to make a protein called penicillinase
that destroys penicillin. Fortunately, scientists have been able to synthesize or make
new antibiotics that penicillinase cannot destroy.
Antibiotics frequently are viewed as a sure cure for whatever ails us and may be
requested when they aren't necessary. For example, antibiotics don't work against
diseases like the flu or sore throats caused by virusviruses
. Inappropriate use contributes to the resistance problem. To stop this trend, you should take antibiotics only when
needed. The proper antibiotic should be chosen and used exactly as directed. Even
though you may feel better after taking the antibiotic for only a few days (since most
of the bacteria causing the infection are killed), you should complete the entire
recommended course for the medication to insure that all the germs are
- How do microbiologists determine which antibiotics are capable of killing particular
- What is the difference between prescription drugs and over-the-counter (OTC)
- Which bacteria are "good" bacteria, and what importance do they play in our lives?
antibiotic a medication made of a natural or synthetic chemical that kills or arrests
a microorganism, primarily bacteria. It is not effective against viruses.
bacteria one-cell microorganisms too small to see with the naked eye but visible when
stained and viewed through a microscope
genetic mutation a process by which a cell's genetic makeup is altered, changing the
cell and those cells it produces. Such mutation can produce an organism resistant to
resistance the natural or acquired ability of a bacterium to escape the harmful effect
of an antibiotic
virus a subcellular particle, far smaller than
most bacteria, that is parasitic and depends on living cells for growth and reproduction
- Beardsley, T. (1992, Nov) Paradise lost? Scientific American, pp. 18-20.
- Begley, S. (1994, Mar 28) Antibiotics: The end of miracle drugs? Newsweek, pp. 46-51.
- Gibbons, A. (1992, Aug 21) Exploring new strategies to fight drug-resistant microbes.
Science, pp. 1036-1038.
- Levy, S.B. (1992) The antibiotic paradox: How miracle drugs are destroying the miracle.
New York: DaCapo Press Inc.
- Levy, S.B. (1993, Apr 14) Confronting multidrug resistance: A role for each of us.
Journal of American Medical Association, pp. 1840-1842.
- Schmidt, K.F. (1992, Oct 26) The troubling ghosts of scourges past. U.S. News & World
Report, pp. 70-71.
Additional sources of information
Centers for Disease Control and Prevention
Center for Infectious Diseases
Office of Public Affairs
1600 Clifton Road NE
Atlanta, GA 30333
American Society of Microbiology
1325 Massachusetts Ave.
Washington, DC 20005
Microbiology laboratory at hospital or clinic
Antibiotics are medications that can kill bacteria, but they are not
bulletproof. The type of bacteria they destroy can vary and bacteria may develop resistance to
antibiotics. Bacteria might undergo genetic changes that prevent the antibiotic from
doing its job. If a bacterial cell is genetically changed it may continue to thrive,
even when treated with an antibiotic.
The following activity demonstrates how antibiotics work and how antibiotic-resistant
bacteria can survive a medication's actions.
- pieces of paper 7.5 cm x 15 cm (3" x 6"), one per person
- straight pins, one per person
- four different color markers--red, yellow, blue, and green
- On three of the pieces of paper, write the word green with the
green marker to represent a trait that stops an antibiotic from working.
- On the remaining pieces of paper, write about an equal number of the
words "red," "yellow," and "blue" in their corresponding ink, one per paper. The colors depict ways
that an antibiotic can destroy a bacterial cell. Blue stands for the destruction of
the cell's genetic material, red for breakdown of the cell wall, and yellow for an
interruption in protein production critical to the cell's life.
- Combine the papers in a container. The participants should pick one
paper each, to represent a specific trait of a bacterial cell, and pin their individual papers onto
their clothes. Once done, each participant should stand next to her or his desk or
- Explain what the blue, red, and yellow colors depict, omitting an
explanation for the green resistance trait. After each color is explained, those "cells" wearing that color should sit down to indicate they've been destroyed by an effective antibiotic.
- Note that three people are still standing, each wearing a green tag.
Explain that these cells represent antibiotic-resistant bacteria that contain a specific trait (the
green tag) which protects them from the antibiotic and leaves them unharmed. In real
life, these cells would survive, living in an environment with fewer bacteria to
compete for food and space than before.
- If a bacterium can divide and produce 2 bacteria every 20 minutes, how
soon will these three surviving resistant germs reach a total of one million organisms? 10
million? 100 million? One billion bacteria? Populations of this size, if pathogenic,
are more than adequate to cause great harm.
- What can happen to bacterial growth when there is little competition for food and
- How can a doctor know for sure that the prescribed antibiotic works against the
bacteria causing a person's sickness?
- How many antibiotics do doctors have at their disposal? Which are the most common
Some bacteria do not cause disease. Within our own bodies, bacteria help us digest the
food we eat and gain access to its nutrients. Research how micro-organisms can be
helpful, such as decomposing leaves and wood, helping make yogurt, and producing
Find out how new drugs are developed, where new drugs might come from in the future,
and what a company must do to receive approval from the U.S. Food and Drug
Administration before a new drug can become available to the public.
Invite a microbiologist or physician with an interest in infectious disease to explain
what antibiotics are and how they work. Discuss tests a lab might run to identify a
bacterial strain and to learn which antibiotics effectively destroy it. Examine
equipment from a lab and discuss the wide variation in types of bacteria.
Bacteria are all around us. Discuss how they can gain a foothold in our bodies-through
a break in the skin, a depressed or immature immune system, or in food. List ways we
can prevent this from happening, including good hygiene; proper food refrigeration,
preparation, and thorough cooking; getting enough sleep and eating a balanced diet;
proper cleaning and care of wounds; and getting vaccinated. What common household
products have the capability to fight bacteria? Are we wise to use these
Newton's Apple is a production of KTCA Twin Cities Public Television. Made possible by
a grant from 3M. Educational materials developed with the National Science Teachers