Biology OL Dr. Sahar A.
Ali
Drugs
A drug is any substance taken into the body that modifies or affects chemical
reactions in the body
Medicinal drugs:
Drugs that help us to stay healthy.
Antibiotics
Antibiotics are medicinal drugs that kill bacteria in the body, without harming our
own cells. They are a very important tool in medicine.
❖ A person’s body needs help in fighting against bacteria and in old ages,
people used to die from diseases which are now harmless for e.g. infected
cuts.
❖ Antibiotics were then discovered, they help to cure bacterial infections that
could be otherwise be very serious or even fatal.
❖ Most of them are made by fungi.
❖ The first antibiotic to be discovered was penicillin
Penicillin
• It is made by the fungus Penicillium.
• Penicillin kills bacteria by stopping them
making their cell walls.
• When a person infected with bacteria is
treated with penicillin, the bacteria are
unable to grow new cell walls and they burst
open.
Penicillin extraction
(later in biotechnology)
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Biology OL Dr. Sahar A. Ali
• As time passed, more antibiotics were developed as bacteria started to
develop resistance against them.
• The more we use the antibiotic, the more selection pressure is put on
bacteria to evolve resistance.
• Antibiotics do not affect viruses as they are not cells and they have nothing
to target in them (for example; in bacteria they target cell walls). So, there
is no point of using them to treat viral infections such as colds.
Resistant bacteria such as (MRSA)
1. They develop due to misuse of antibiotics by not completing the course as
instructed by doctors.
2. Usage of antibiotics in treating viral infections.
3. Using antibiotics in treating animals.
Measurements to avoid developing resistant bacteria
It’s very important to restrict the use of antibiotics as much as we can.
1. Saving some antibiotics to be expensive and not available for the public to
be used after major surgical operations.
2. Don’t prescribe antibiotics for viral infections.
3. Completing the course of antibiotics to avoid resistance development.
4. Avoid using antibiotics in treating animals.
5. Vary the type of antibiotics with every time of infection.
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