Vaccinations and Resistance

Vaccination
1. Protects from future infections
  1. Involves injecting small amounts of dead or inactive microorganisms. E.g MMR used to vaccinate measles, mumps and rubella.
    1. They carry antigens, making your body's white blood cells produce antibodies to attack them
      1. Booster injections may be given to increase levels of antibodies again
2. When infected with a new microorganism it takes white blood cells a few days to learn how to fight it
  1. Most times it's too late and you'll be really ill
3. Pros
  1. Control infectious diseases that were once common
    1. Eg. Polio, measles, rubella mumps etc.
      1. Eliminated smallpox and polio has fell by 99%
  2. Epidemics can be prevented if a large percentage is vaccinated
    1. Unvaccinated people are unlikely to catch the disease as there are fewer people to pass it on
4. Cons
  1. They don't always work
  2. Bad reactions/side effects to the vaccine eg. swelling, fever, seizures. But they are rare
Drugs
1. Relieve symptoms
  1. Painkillers relieve pain
  2. Reduce symptoms without tackling the underlying cause
    1. Eg. cold remedies don't cure colds
2. Cure the problem
  1. Antibiotics (penicillin) kill bacteria causing the problem without killing body cells
    1. Different antibiotics kill different types of bacteria
    2. Don't destroy viruses
3. Resistance
  1. Mutations can make them resistant to antibiotics
  2. When you treat the infection only non-resistant bacteria will get killed
    1. Resistant bacteria will survive and reproduce and the population will increase
      1. Can cause serious infection which can't be treated my antibiotics
        Eg. MRSA (methicillin-resistant Staphylococcus aureus) causes serious wound infections
  3. To slow down the rate
    1. Important for doctors to avoid over-prescribing antibiotics
Investigating antibiotics
1. Microorganisms are grown (cultured) in a culture medium.
  1. Agar jelly containing carbohydrates, minerals, proteins & vitamins needed to grow
    1. Hot agar jelly is poured in Petri dishes and when cooled inocculating hoops transfer microorganisms where they will multiply
      1. Paper discs soaked in different antibiotics are placed on the jelly
        Resistant ones will continue grow non resistant will die
2. Everything needs to be sterilised beforehand so no unwanted microorganisms will interfer
  1. Inocculating hoop is passed through a flame
  2. Lid is taped
3. In school labs they are kept at 25°C - less likely for harmful pathogens to grow
4. In industrial conditions they are incubated at higher temperatures to grow faster

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Vaccinations and Resistance

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