Antibiotics & Painkillers (AQA GCSE Combined Science: Trilogy: Biology): 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 – e.g. antibiotics

  • Medicines that treat the symptoms of the disease – e.g. 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 deaths from infectious bacterial diseases

• Only certain antibiotics will work on certain diseases; however, 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 bacterial cellular processes such as the production of the cell wall – they affect processes usually only in bacteria, so they are not harmful to animal cells

Diagram of penicillin action

Use this image

• 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 (e.g. 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

Use this image

• 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 the 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, known as MRSA (methicillin-resistant Staphylococcus aureus), has developed resistance to the powerful antibiotic methicillin

  • MRSA can infect wounds and is difficult to treat without antibiotics

Diagram of antibiotic resistance spread in bacteria

Use this image

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 should not be used in non-serious infections that the immune system will ‘clear up’

  • antibiotics should not 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

  • antibiotic 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