Effect of antibiotics.pdf

drugs effects on human being

1. EFFECTS OF
ANTIBIOTICS ON
MICROORGANISMS

2. INDEX
 Introduction
 History and Discovery
 Goals
 How do antibiotics work?
 Why are antibiotics important?
 Resistance:
 Antibiotic Resistance
 How is Resistance spread?
 7 Types of antibiotics
 5 Basic mechanism of antibiotic action
against bacterial cell
 Pros of taking antibiotics
 Side effects of taking antibiotics
 Experiment:
 Aim
 Materials Required
 Procedure
 Observations
 Conclusion
 Bibliography

3. INTRODUCTION

Antibiotics are chemicals that kill or inhibit the
growth of bacteria and ae used to treat bacterial
infections. They are produced in nature by soil
bacteria and fungi. This gives the microbe an
advantage when competing for food and water and
other limited resources in a particular habitat, as
the antibiotic kills off their competition. Only
substances that target bacteria are called
antibiotics.
 Antiseptics are used to sterilize surfaces of living
tissue when the risk of infection is high, such as
during surgery.
 Disinfectants are non-selective antimicrobial,
killing a wide range of micro-organisms including
bacteria. They are used on non-living surfaces, for
example in hospitals.

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4. HISTORY AND DISCOVERY

In 1928, at St. Mary Hospital, London, Alexander
Fleming discovered Penicillin. Fleming was, a bit
disorderly in his work and accidently discovered
penicillin. Upon returning from holiday in Suffolk in
1928, he noticed that a fungus, Penicillium notatum,
had contaminated a culture plate of Staphylococcus
bacteria he had accidently left uncovered.
The discovery of penicillin changed the world of
medicine enormously. With its development,
infections that were previously severe and often fatal,
like bacterial endocarditis, bacterial meningitis and
pneumococcal pneumonia, could be easily treated.
Antibiotics were widely used for treating soldiers
during World War II, caring for battle wound
infections and pneumonia. By the mid-to-late 1940s,
it became widely accessible for the general public.

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5. GOALS

1. To study the effect of antibiotics on
micro-organisms(bacteria).
2. To understand its mechanism.
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6. HOW DO ANTIBIOTICS
WORK ?

Antibiotics are used to treat bacterial infections.
Antibiotics take advantage of the difference between
the structure of bacterial cell and the host’s cell.
They either prevent the bacterial cells from
multiplying so that the bacterial population remains
the same, allowing the host’s defense mechanism to
fight the infection or kill the bacteria, for example
stopping the mechanism responsible for building
their cell walls.
An antibiotic can also be classified according to the
range of pathogens against which it is effective.
Penicillin G will destroy only a few species of bacteria
and is known as narrow spectrum bacteria.
Tetracycline is effective against a wide range of
organisms and is known as broad spectrum bacteria.
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7. WHY ARE ANTIBIOTICS
IMPORTANT?

The introduction of antibiotics into medicine
revolutionized the way infectious diseases were
treated. Between 1945 and 1972, average human life
expectancy jumped by eight years, with antibiotics
used to treat infections that were previously likely to
kill patients. Today antibiotics are one of the most
common classes of drugs used in medicine and make
possible many of the complex surgeries that have
become routine around the world.
If we ran out of effective antibiotics, modern
medicine would be set back by decades. Relatively
minor surgeries, such as appendectomies, could
become life threatening, as they were before
antibiotics became widely available. Antibiotics are
sometimes used in a limited numbers of patients
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8. before surgery to ensure that patients do not contact
any infections from bacteria entering open cuts.
Without this precaution, the risk of blood poisoning
would become much higher, and many of the more
complex surgeries doctors now perform may not be
possible.




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9. RESISTANCE
1. Antibiotic resistance

Bacteria are termed drug-resistant when they are no
longer inhibited by an antibiotic to which they were
previously sensitive. The emergence and spread of
antibacterial-resistant bacteria has continued to grow
due to both the over-use and misuse of antibiotics.
Treating a patient with antibiotics causes the
microbes to adapt or die; this is known as ‘selective
pressure’. If a strain of a bacteria species acquires
resistance to an antibiotic, it will survive the
treatment. As the bacterial cell with acquired
resistance multiplies, this resistance is passed on to
its offspring. In ideal conditions some bacterial cells
can divide every 20 minutes; therefore after only 8
hours in excess of 16 million bacterial cells carrying
resistance to that antibiotic could exist.

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10. 2. How is resistance spread?

Antibiotic resistance can either be inherent or
acquired. Some bacteria are naturally resistance
to some antibiotics due to their physiological
characteristics. This is inherent resistance.
Acquired resistance occurs when a bacterium
that was originally sensitive to an antibiotic
develops resistance. For example, resistance
genes can be transferred from one plasmid to
another plasmid or chromosome, or resistance
can occur due to a random spontaneous
chromosomal mutation.

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11. 7 TYPES OF ANTIBIOTICS

Although there are well over 100 antibiotics, the
majority come from only a few types of drugs. These
are the main classes of antibiotics.





ANTIBIOTIC EXAMPLE
PENICILLIN amoxicillin
CEPHALOSPORINS cephalexin
MACROLIDES erythromycin
FLUOROQUINOLONES ofloxacin
SULPHONAMIDES bactrim
TETRACYCLINES tetracycline
AMINOGLYCOSIDES gentamicin
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12. FIVE BASIC MECHANISMS OF
ANTIBIOTIC ACTION
AGAINST BACTERIAL CELLS:

 Inhibition of cell wall synthesis (most common
mechanism).
 Inhibition of protein synthesis (translation).
 Alteration of cell membranes.
 Inhibition of Nucleic acid synthesis.
 Antimetabolite activity.

The ribosome is a major target for Antibiotics.
Drugs inhibit ribosome function either by
interfering in messenger RNA translation or by
blocking the formation of peptide bonds at the
peptidyl transferase centre. These effects are the
consequence of the binding of drugs to ribosomal
subunits.


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13. PROS OF TAKING
ANTIBIOTICS:

 Antibiotics can slow down the growth of bacteria
and kill many types of infections.
 In some cases, such as before surgery, antibiotics
can prevent infection from occurring.
 Antibiotics are fast acting ; some will begin
working within a few hours.
 They are easy to take; most Antibiotics are oral
medications. Your doctor may decide to give you
an injection, if it is imperative that the medicine
gets into your system quickly.


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14. SIDE EFFECTS OF
TAKING
ANTIBIOTICS:

The most common side effects of antibiotics is- it
affects the digestive system. Antibiotics commonly
cause the following side effects:
 Diarrhea
 Nausea
 Vomiting
 Rash
 Upset stomach
 Sensitivity to sunlight, when taking tetracycline
 With certain antibiotics or prolonged use, fungal
infections of the mouth, digestive tract, and
vagina.


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15. EXPERIMENT
AIM: To see the effect of antibiotics on bacteria
count.
MATERIALS REQUIRED :
 10 test-tubes of sterilized water
 10 PCA(Agar) plates
 Bunsen burner
 Graduated cylinder
 Ethanol (Used for sterilizing; just flame is enough
most cases)
 Glass hockey stick
 Pipettes
 Refrigerator
 Incubator (A warm cabinet for growing bacteria)
 Scale
 Large beaker
 Hot plate
 Sample antibiotic

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16. PROCEDURE:
Step 1:
Prepare a culture media plate for growing bacteria.
Step 2:
Get a sample of polluted water for test. Mix 2 ml of
polluted water with 10 ml chicken broth in a test tube
and incubate it for 24 hours so the bacteria will
reproduce and increase. Usually this is done on a
device that constantly moves, so the bacteria can
freely move in the liquid. Most likely you will not have
a vibrator, so it is good if you shake the test tube a
few times during this incubation period.
Step: 3
While the bacteria are being incubated, prepare
some antibiotic disks as described here. (Antibiotic
disks can also be purchased from biology suppliers.)
Break an antibiotic capsule (here using Ampicillin)
and empty the contents in a clean petri-dish. One
capsule will be enough for hundreds of disks.
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17. Dispose of the plastic shell and add a few drops of
water to the remaining powder. Cut some filter
papers in small pieces and soak them in the antibiotic
solution. Let the disks dry in a clean space. You may
cover them with another filter paper to protect them
from dust.


Although they are known as antibiotic disks, you can
cut them in small squares.

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18. The reason that we use filter paper, is that other
papers often have starch and other polymers that
may affect the results of our experiments. Filter
paper is pure cellulose fiber.

Step 4:
Use the bacteria that you have grown in step 2 and
prepare dilution of bacteria.
1. Prepare 1:10 dilution of the sample. To do this, take
2ml of the sample and blend it with 18ml of distilled
water.
2. Pipette 0.1ml of each dilution onto a Plates Count
Agar (PCA) plate.
3. Take a glass hockey stick submersed in ethanol and
run it through a flame to sterilize it. (Glass hockey
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19. stick is a glass rod bent on one end like a hockey
stick. It is used to spread bacteria on the surface of
agar plate. You may use a steel spoon instead.)
4. Let it cool and use it to spread dilution around the
plate.
5. Do this on two plates for each of the five different
dilutions.
6. Place an antibiotic disk on the plate of dilution.
7. Incubate the plate at 35 degrees Celsius for 24
hours and then count the bacterial colonies.
8. Take 3 nutrient agar plate and added 0.5ml of the
solution on each of plates.
9. Leaving one plate without any antibiotics, placing
one antibiotic disk on the second plate and two
antibiotic disks on the third plate. All plates were
incubated for 48 hours.








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20. OBSERVATIONS:







PCA1

PCA2
PCA3
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21. CONCLUSION:

The growth of bacteria around the antibiotic disks
is less. Inhibition zones are more in the plates with
more antibiotic disks.
Hence, antibiotics stop the proliferation of
bacteria.









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22. BIBLIOGRAPHY:

www.emedicinehealth.com
microbiologysociety.org
www.scienceproject.com
medicalnewstoday.com
www.scribd.com
www.studocu.com

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