Transcript Antibiotics - University of Arizona

“The World We Create”
NATS 101
Section 6
Project 4!
Due Tuesday May 4th
Final Exam!
Week April 27-29!
UNIT 4:
A world of drugs, a
blessing or a curse?
Antibiotics
Expected Learning Outcomes:
• Explain what antibiotics are and how they
work;
• Make decisions about when to take
antibiotics;
• Diagram the process of bacterial
resistance;
• Understand the consequences of bacterial
resistance.
Case Scenario #1
You tell her:
– A. “You need to get to a doctor! They
will give you some antibiotics to make
you feel better.”
– B. “You should take some Tylenol to
make the pain go away.”
– C. “You should just rest and try using
some throat spray or cough syrup.
Make sure you have good soft tissues.”
Case Scenario #2
– A. “I need to get to a doctor! They will give me antibiotics
that will make me feel better.”
– B. “When I get home, I will try taking some Tylenol to make
the pain go away.”
– C. “It’s probably nothing. Maybe I’m just nervous that Vicente
will give us a pop quiz. I’m sure it will go away soon.”
Case Scenario #3
 A. “First thing in the morning, I am getting myself into the
doctor. They will give me some antibiotics to make me feel
better.”
 B. “I should take some Tylenol.”
 C. “It’s probably nothing. Maybe I am over-worked from
being so busy yesterday. I’m sure it will go away soon.”
What did you decide?
Scenario 1
Scenario 2
Antibiotics, Tylenol, Cough Syrup/Throat Spray
Scenario 3
Antibiotics, Tylenol, Take no action
Antibiotics, Tylenol, Take no action
Would I Take Antibiotics For…?
Urinary Tract Infection
Dog Bite
Yeast
Infection
Pink Eye
Bladder Infection
Strep Throat
Broken arm
Flu
Common Cold
Pneumonia
Herpes
• When do doctors prescribe antibiotics?
• What instructions are given when antibiotics
are prescribed?
• How important are these instructions?
Do we need to follow all of them?
What do antibiotics do?
- Antimicrobial drugs can
work against protozoa,
bacteria or fungus.
**They don’t stop viruses**
X
- Antibiotics specifically work
against bacteria.
How do Antibiotics work?
Different Mechanisms:
- Weaken the cell wall,
causing cells to lyse;
- Block DNA
transcription;
- Stop protein
synthesis so the
cell can’t make
essential components
such as flagella
- Enhance immune
system
Would an antibiotic work?
Bacteria or Virus?
Urinary Tract Infection
Dog Bite
Pink Eye
Yeast Infection
Common Cold
Bacteria
Flu
Strep Throat
Pneumonia
Bladder Infection
Broken arm
Herpes
Virus
Why do we have to be careful?
- Why do Doctors tell us we MUST TAKE ALL
of our prescribed antibiotics?
- What are the
consequences of
not doing this?
Let’s See What Happens…
We are going to pretend that we are all
different types of bacteria!
If you are a blue, green, or yellow bacteria,
you are considered a “good” bacteria; red is
considered a “bad” bacteria.
Each row represents a new day in the life of
our host body.
Each new day, we are analyzing a sample of
the total bacteria present in our host body.
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
Day 11
Day 12
Day 13
Day 14
So, What Happened?
What did you observe?
(What happened to the good bacteria?
The bad bacteria? At the end of treatment?)
HOW CAN THIS BE EXPLAINED?
Is this bad? Why?
Why do we have to be careful?
When taking antibiotics…
- “Feeling better” does not necessarily mean that
all of the harmful bacteria is gone.
- There is a vast amount of variation within
bacteria populations.
- Individual bacterium have different levels of
resistance to certain antibiotics.
- As a result, some bacteria can withstand a
higher concentration of antibiotics.
Why do we have to be careful?
Antibiotic Resistance: The ability of bacteria to resist
or overcome the effects of an antibiotic.
Within a species, bacteria
can be grouped based on
their variable resistance.
These are called strains.
Antibiotic resistance arises through the process
natural selection.
Natural Selection
Individuals in a population are variable
Some variations give certain
individuals a better chance
of survival and/or a higher
reproduction rate under
certain “environmental
pressures.”
Natural Selection
These variations are heritable, meaning they get
passed on to any offspring the individual has.
Those individuals with a variation
that let them survive better and
produce more offspring will
represent a higher proportion of the
final population than they did in the
original population.
Antibiotic Resistance
1 Antibiotic kills susceptible bacteria in
population;
2 Resistant strains survive;
3 Less competition = easier life = lots of
reproduction = higher percentage of
resistant strains in final population.
2
1
3
Resistance: A Growing Problem
Bacteria divide very rapidly
-Once every 20 minutes!
If you start with a single resistant bacteria…
1 hour
8
6 hours
262144 
12 hours
24 hours
6.871 x1010  4.722 x 1021
Why is this a problem?
This speeds up the process of natural selection and
evolution through mutation!
Resistance can spread through a population very quickly!
Resistance: A Growing Problem
1967: “It is time to close the book on
infectious diseases. The war against
pestilence is over.”
1998: “Infectious Diseases a Rising Peril –
Death Rates up 58% in US since 1980”
2002: World data from the CDC reports
respiratory infections (influenza,
pneumonia) as the #4 cause of death
That’s 3.9 million people!
Resistance: A Growing Problem
The useful
lifespan of an
antibiotic is
limited due to
the increasing
prevalence of
resistance.
MRSA
MRSA Infection Rates
70%
Percent Infections MRSA
CDC estimated that
94,360 invasive MRSA
infections occurred in
the United States in
2005;
18,650 of these were
associated with
death.
60%
50%
40%
30%
20%
10%
0%
1974
1995
Year
2004
How we’re contributing to the problem
So why has resistance risen so dramatically in
the past 20 years?
What are the potential consequences
(social, economical) of this problem?
Causes?
 Over-prescription of antibiotics;
 Overuse of antibiotics in animal feed;
 Scarce research and development in the
field of antibiotic pharmaceuticals;
 Advances in medicine & society.
What Are the Consequences?
Bacterial Resistance
More Carriers
More Infection
New Treatments
New Drugs
Unknown Consequences
$$$
Stronger Drugs
Worse Side Effects
Why All These Rules?
• Take only those antibiotics that are prescribed for you—don't
take someone else's antibiotics, or antibiotics that you find
around the house.
• Don’t ask for a stronger antibiotic.
• When a doctor prescribes an antibiotic for you, take all of it as
directed.
• When you’re sick, rest. Don’t go back to your normal routine
just because you think the antibiotic will handle the problem.
In your groups, determine the rationale behind each
of the guidelines given with a prescription for
antibiotics. Why do doctors tell you these things?
You have 5 minutes