Consequences of Antibiotic Resistance (Cambridge (CIE) A Level Biology): Revision Note

Consequences of antibiotic resistance

• Antibiotic-resistant strains are a major problem in human medicine

  • Incidence of resistance is increasing due to antibiotic use in humans and in livestock farming when they are not needed

  • By using antibiotics frequently, a selection pressure is exerted on the bacteria

    • This drives selection for resistant individuals

• Commonly prescribed antibiotics are becoming less effective against some bacterial strains

• Some strains of bacteria can be resistant to multiple antibiotics, making diseases very difficult to treat

  • These bacteria are commonly known as superbugs

  • The most common example is a strain of Staphylococcus aureus that has developed resistance to an antibiotic called methicillin, and is now known as MRSA (Methicillin-resistant Staphylococcus aureus)

• Infections caused by resistant strains of bacteria often need to be treated using multiple antibiotics

  • This results in complicated and expensive treatments that may not be available to all

Reducing antibiotic resistance and its impact

• Ways to prevent the incidence of antibiotic resistance include:

  • tighter controls in countries where antibiotics are sold without a prescription

  • doctors prescribing antibiotics only when needed, e.g. antibiotics not being used for viral infections

  • avoiding the blanket use of ‘wide-spectrum’ antibiotic, and instead prescribing specific antibiotics for different types of infection

  • tighter control of antibiotics in agriculture

• The spread of already-resistant strains can be limited by:

  • ensuring good hygiene practices, such as handwashing and the use of hand sanitisers, especially in clinical environments

  • isolating infected patients to prevent the spread of resistant strains, in particular in surgical wards where MRSA can infect surgical wounds

• Scientists need to find new antibiotics to which bacteria have not yet been exposed, as well as antibiotic alternatives

  • However, this process is expensive and time-consuming