Topic 6

• Antibiotics are drugs that destroys microorganisms or prevent them from reproducing. Work with bacteria but not viruses.
• selective toxicity - interfering with pathogens but with minimal damage to human host cells
• a bacteriostatic antibiotic is one that completely inhibits the growth of microorganisms. example tetracycline
• a bactericidal antibiotic is on that destroys almost all bacteria. Example penicillin
• Bactericidal antibiotics are used in severe and dangerous infections, or when someone’s immune system is suppressed
• a broad spectrum antibiotic destroys a wide range of harmful and good bacteria, and other pathogens
• a narrow spectrum antibiotic targets one or two specific bacteria
• what does effectiveness of an antibiotic depend on?

  concetration. local ph. susceptibility of pathogen.
• antibiotic resistance is caused by mutations. eg. change in active site of an enzyme, change to ribosomes or change to transport proteins.
• vertical gene transfer is through binary fission, and all the genes are passed down through generations. a population can quickly become resistant. this is due to natural selection
• horizontal gene transfer is done by conjugation. plasmids are transferred through a pilus into another cell, creating two identical cells.
• how can hygiene be used to control spread of resistance?

  hand gels. isolation of infected patients. screening on arrival. cleaning.
• Endotoxins are lipopolysaccharides. They are part of the cell membrane.
• Are endotoxins gram negative o r positive or both?

  negative
• are exotoxins gram negative, positive or both?

  both
• Exotoxins are soluble proteins that are released from reproducing bacteria in the host cell
• effects of exotoxins: damages cell membranes, poison, act as competitive inhibitors (which can cause internal bleeding)
• effects of endotoxins: fever, vomit
• what is disease is caused by endotoxins?

  salmonella
• what disease is caused by exotoxins?

  staphylococcus
• the humoral immune response is the action of B cells producing antibodies, it’s associated with the non-cellular part of blood
• cell mediated immune response is the production of specialised lymphocytes called T cells
• where are B lymphocytes found?

  bone marrow, femur
• where are T lymphocytes matured at?

  thymus gland
• How is stem rust fungus spread between plants?

  wind
• cereal crops and berberis are most affected by stem rust fungus
• symptoms of stem rust fungus:

  • weakened stem
  • water loss
  • pustles on epidermis
• stem rust fungus infects plants with spores. they germinated on the plant, and produce hyphae which enter via the stomata. it grows into mycelium , which produces enzymes that digest plant and absorb nutrients.
• treatment of flu:

  • antiviral medication
  • antibiotics (secondary infections)
  • painkillers (for symptoms)
• symptoms of flu:

  • headache
  • coughing sneezing
  • muscular joint pain
  • fever
• how is flu passed on?

  droplet infection. direct contact.
• influenza antigen binds to receptor on host cell and injects viral dna. biochemistry taken over, cell produces new virus particles. cell lysis, so viruses released
• active natural immunity is our immune system. Antibodies are formed, pathogens are destroyed.
• passive natural immunity - antibodies are passed to the baby from mother during pregnancy, and from breast milk (particularly colostrum). Immunity is only temporary, as antibodies are not replaced.
• active artificial immunity is vaccines. a small amount of antigen or dead pathogen is inserted into blood stream. immune system produces antibodies, so memory cells form, and will attack quicker if we actually get the disease.
• passive artificial immunity - antibodies are formed in someone and extracted and given to someone else. temporary as cannot be replaced
• eradicating - if the pathogen is completely non-existent. eg small pox. the pathogen only exists in 2 labs in the world.
• elimination - the disease is gone but pathogen remains present in animals or soil. immunisation continues. eg polio
• what % need to be vaccinated for herd immunity to be effective?

  80
• pros of vaccination

  • protection of yourself
  • protection of others
  • treatment costs kept low