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Antibiotics & Painkillers (AQA GCSE Biology: Combined Science)
Revision Note
Antibiotics & Painkillers
- When treating a disease there are two types of medication that an individual can take:
- Medicines that treat the cause of the disease – antibiotics
- Medicines which treat the symptoms of the disease – eg. painkillers
- Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body
- The use of antibiotics has greatly reduced the deaths from infections in the last century
- Only certain antibiotics will work on certain diseases, however, so a doctor will prescribe different antibiotics depending on the type of infection (see Culturing Microorganisms)
- It is important that specific bacteria should be treated by specific antibiotics that are known to work against them
- Antibiotics work by stopping bacteria cellular processes such as the production of the cell wall – they affect processes usually only in bacteria so are not harmful to animal cells
Penicillin was the first antibiotic to be discovered and is widely used, although resistance is a problem
- Antibiotics will not work against viruses, as viruses reproduce inside cells. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues
- Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens (eg. ibuprofen can reduce pain and inflammation)
Antibiotic Resistance
- The use of antibiotics has increased exponentially since they were first introduced in the 1930s
- In that time they have saved millions of lives
The introduction of antibiotics has had one of the largest impacts on global health, shown by this example in the USA
- However, since their discovery and widespread use, antibiotics have been overused and antibiotic resistance has developed in many different types of bacterial species
- Bacteria, like all organisms, have random mutations in their DNA
- One of these mutations may give them resistance to an antibiotic
- If an organism is infected with bacteria and some of them have resistance, they are likely to survive treatment with antibiotic
- The population of the resistant bacteria will increase
- If the resistant strain is causing a serious infection then another antibiotic will be needed
- A strain of Staphylococcus aureus has developed resistance to a powerful antibiotic methicillin, this is known as MRSA (Methicillin resistant Staphylococcus aureus)
- MRSA can infect wounds and is difficult to treat without antibiotics
Bacteria evolve rapidly as they reproduce quickly and acquire random mutations – some of which confer resistance
Preventing resistant bacteria
- To reduce the number of bacteria that are becoming resistant to antibiotics:
- Doctors need to avoid the overuse of antibiotics, prescribing them only when needed – they may test the bacteria first to make sure that they prescribe the correct antibiotic
- Antibiotics shouldn't be used in non-serious infections that the immune system will ‘clear up’
- Antibiotics shouldn't be used for viral infections
- Patients need to finish the whole course of antibiotics so that all the bacteria are killed and none are left to mutate to resistant strains
- Antibiotics use should be reduced in industries such as agriculture – controls are now in place to limit their use in farming
Reducing the spread of resistant strains
- Good hygiene practices such as handwashing and the use of hand sanitisers have reduced the rates of resistant strains of bacteria, such as MRSA, in hospitals
- The isolation of infected patients to prevent the spread of resistant strains, in particular in surgical wards where MRSA can infect surgical wounds
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