Vaccination
What
Vaccination is active artificial immunity.
We can be made immune to a disease without actually becoming infected by that disease
Mechanism
a person is given an ‘agent’ that carries the same antigens as a particular disease causing
microorganism
Mode of vaccination
1, injection
2.oral (by mouth)
3.nasal
How body response
Lymphocytes recognise the antigens
multiply exactly as if that microorganism had entered the bloodstream
They form memory cells and make us immune to the disease
Characteristics of Vaccine
1.a harmless strain of the actual microorganism, e.g. the vaccines for polio, tuberculosis and
measles
◾◾ dead microorganisms, e.g. the vaccines for typhoid and whooping cough
◾◾ modified bacterial toxins, e.g. the toxins of the tetanus and diphtheria bacteria
◾◾ the antigens on their own, e.g. the influenza (‘flu) vaccine
◾◾ harmless bacteria, genetically modified to carry the antigens of a different pathogen, e.g. the
hepatitis B vaccine
Protection years
give protection for many years, even a lifetime.
Some vaccinations are not so effective and extra ‘booster’ injections -to maintain a person’s
immunity.
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Before travelling
Vaccination is needed for Endemic diseases (Thyphoid)
Before they travel to foreign countries, people need to take advice from their doctor about any
vaccinations that may be necessary
Eradicated disease
Small pox -completely wiped out by disease
Smallpox is a highly infectious disease caused by a virus
In the 1960s, the World Health Organization started a worldwide programme with the aim of
completely eradicating smallpox.
Vaccination programme included
Vaccinations
isolation of patients with the disease
observation to detect new cases.
The programme was successful..The last case of smallpox was identified in 1977, and in 1980
the world was officially declared free of the disease.
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Antibiotics
What Antibiotics are chemicals that kill microorganisms, or reduce their growth.
Uses to treat bacterial infections
to treat fungal pathogens. (few)
Antibiotics do not work on viruses, so they are no use in treating any
disease caused by a virus.
Natural antibiotics - produced by bacteria and fungi.
They are used by the bacteria and fungi to kill other microorganisms.
-first antibiotic -discovered in 1929 -made by the mould fungus Penicillium, and is called
penicillin.
Penicillin kills bacteria.
It was first isolate and used to treat bacterial infections in the 1940s.
other natural antibiotics
- streptomycin and chloramphenicol (both made by bacteria). Many more artificial antibiotics
have been made.
-Some are semi-synthetic, chemically-altered versions of natural antibiotics;
others are fully synthetic chemicals that have been ‘designed’ in a laboratory.
Types
bactericidal. -Antibiotics that kill bacteria
bacteriostatic - Antibiotics that just stop them reproducing
Broad spectrum antibiotic -which act against a range of bacteria, while others are more
limited in their target.
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Three antibiotics and the ways in which they act.
cold and ‘flu are caused by viruses, so antibiotics are useless against them
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Antibiotic Resistant Bacteria
Reasons/Causes
1.Increase use of antibiotics over the last 20 years. (given an antibiotic for even the most minor
of illnesses)
2Wrong use of antibiotics(Irregular dose, incomplete course,.poor compliance of patient,
incomplete cessation of antibiotic therapy, dose and course insufficiency)
Result
the antibiotics are no longer effective in preventing bacterial infection.
Mechanism
a random gene mutation.
In a place where the antibiotic is widely used, the new resistant bacterium has a big advantage
over non-resistant bacteria of the same type.
The resistant strain of bacterium will survive and multiply in greater numbers than the non-
resistant type.
bacteria reproduce very quickly(divides every 20 minutes produces 72 generations in a single
day) -results in a population of millions of resistant bacteria.
Examples of Antibiotic resistant Bacteria’
worrying example -MRSA. (methicillin-resistant Staphylococcus aureus.)
- a ‘super bug’ because it is resistant to many antibiotics (including methicillin, a type of
penicillin that is no longer used)
- a major problem in hospitals, where it is responsible for many infections that are difficult to
treat.
Resistant bacteria -not be killed by the antibiotic, so the antibiotic is no longer effective in
controlling the disease.
Bacterial resistance to antibiotics
- first noticed in hospitals in the 1950s,
- a major problem today.
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Prevention of Antibiotic Resistance
1.Right ridiculous use of antibiotic(right time, right dose, right course)
2.Dont start the very potent antibiotic in minimal infection
3.Explain the patients to take antibiotic right time, right dose
How to test antibiotic resistance
Procedure
Interpretation
The circular white discs contain different antibiotics.
The clear areas around the discs show where the bacteria have been killed by the antibiotic
diffusing into the agar.
If the antibiotic does not work against the bacterium (e.g. due to resistance), there will
be no clear area around the disc.
ANTIBIOTICS BEING TESTED FOR
THEIR EFFECTIVENESS IN KILLING A SPECIES OF BACTERIUM.
