Antibiotics & Painkillers (AQA GCSE Biology)

• 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)

• 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