Medicines
Different types of medicines are available to treat many different communicable and non-communicable Illness affecting plants and animals.. Some medicines only treat the symptoms and others cure the disease by killing the Microorganism that causes disease.. Many non-communicable diseases can be managed long-term with medicines.
A chemical taken to relieve pain associated with disease. are chemicals that relieve the symptoms but do not kill the pathogens. Common examples include paracetamol and aspirin, which can relieve the symptoms of a common cold or a sore throat.
As only the symptoms are treated, your immune system still needs to combat the pathogen.
Antibiotics
Substance that controls the spread of bacteria in the body by killing them or stopping them reproducing. are substances that slow down or stop the growth of Single-celled microorganisms, some of which are pathogenic in humans, animals and plants. Singular is bacterium.. They are commonly prescribed medicines, examples include An antibiotic produced by a fungus, Penicillium. Discovered by Alexander Fleming. and A frequently prescribed antibiotic, particularly for children. It is an effective treatment for ear and throat infections.. Antibiotics can be taken to cure the disease by killing the bacterial pathogen, like the sexually transmitted disease gonorrhoea. They do not kill viruses and so cannot be used for viral pathogens like the common cold.
Penicillin was the first antibiotic discovered by Alexander Fleming in 1928. He noticed that some bacteria he had left in a A clear glass or plastic dish, used to grow living cells from organisms so they can be studied. had been killed by the naturally occurring Penicillium A type of fungus..
How do antibiotics work?
Antibiotics damage the bacterial cells but do not damage the host cells. They have the ability to cure some bacterial diseases that would have previously killed many people. Since their introduction, they have made a major contribution to the world's health.
Different bacteria cause different diseases. Some antibiotics may only work against one type of bacteria, or a few types. This means that different antibiotics are needed for the treatment of the range of bacterial diseases.
Antibiotic resistance
The ability of bacteria to survive exposure to antibiotics. It is caused by mutations in their genes. has now become a common problem. All populations have variation, and resistance of bacteria to an antibiotic can be brought about by just one mutation in a single gene. As bacteria reproduce by binary fission, the number of bacteria with this mutation can increase very quickly. The non-resistant bacteria are destroyed by the antibiotics, which removes competition. With no competition for space and food, the resistant genetic variant can spread quickly.
Bacteria can be tested for resistance to specific antibiotics. Bacteria are spread on an agar plate to make a 'bacterial lawn'. Paper discs soaked in antibiotic are placed on the agar and then incubated. After several days there are clear areas around the discs containing antibiotics which can kill that strain of bacteria. There are no clear areas around discs containing antibiotics that the bacteria are resistant to.
The effectiveness of each antibiotic can be measured by calculating the area of each clear zone around each disc:
- Measure the diameter of the clear zone and work out the radius. radius \((r) = \frac {1}{2}~ \text{diameter~in~mm}\).
- Work out the area using the equation area = \( \pi {r^2}\).
The clear zone with the largest area is the most effective antibiotic.
Question
A disc containing penicillin made a clear area 18 mm across on a bacterial plate. What is the area of the clear zone?
\(r\) = 18 mm 梅 2 = 9 mm
\(area = \pi {r^2} = 3.14 \times 9^2 = 250~mm^2\) (to 2 significant figures).
Hint: When asked to do a calculation you need to be aware of the number of significant figures to use in your answer. A general guide is to use the same number of significant figures as the lowest number of significant figures used in the inputs to the calculation. In this case 18 mm is two significant figures and pi (3.14) is given to three significant figures, so use two significant figures in your answer.
We cannot stop bacteria mutating because it is a natural process that takes place in all populations of organisms. However, we can make it more difficult for resistant bacteria to spread.
- Only prescribe antibiotics to people who really need them.
- Be sure that patients finish the course of antibiotics (unless harmful side-effects develop). The most resistant bacteria are the last ones to be killed by the antibiotic.
- Maintain good hygiene in hospitals to reduce the spread of antibiotic-resistant bacteria.
Viral diseases
Viral diseases cannot be cured by antibiotics, as they reproduce inside the host cells. Medicines called antiviral drugs have been developed to slow down the replication of the virus inside the patient, and so make the infection less severe. Antiviral drugs are difficult to develop.
Viruses have proteins on their outside called antigens. Your body detects these and your immune system starts to protect you against the infection. In some viruses, like the flu, these antigens change frequently meaning new vaccines are required. There is a new vaccine for the flu virus each year.