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Antibiotics, Viruses, and Prions
Bacterial Infections• Colonization by harmful
bacteria• Using the body as resources to
grow and reproduce• Battled by the immune system• Different numbers of bacteria
needed to overwhelm the immune system and cause infection• Shigella: 10• E. coli: 100
How Antibiotics Work• 2 main methods• Kill bacteria outright• Prevent bacteria from growing
• Usually bind to bacteria to do this• Generally stop bacteria from making something• Cell wall, proteins, DNA, etc.• The more similar that target to your cells, the more toxic the
antibiotic is to you
How Antibiotics Work• Antibiotics reduce the population of invading bacteria• Survivors usually dealt with by immune system
• Start to feel better before using all of the medicine• Feel better before the population is reduced to the point that the
infection is defeated• Stopping the medication before this point leaves bacterial
survivors
Antibiotic Resistance• Surviving bacteria have time to
adapt to drug• Drug loses effect • Trait passed in population• Treatment with same drug now
ineffective
How do we deal with this?• Hospitals:• Serious infections get multiple antibiotics at the same time• Bacteria that are immune to one probably aren’t immune to the
others
• Personal: take ALL of your antibiotics as prescribed, even if you feel better before you run out of medicine• If the bottle says take for 7 days, take for 7 days, not 4
Viruses• Obligate intracellular parasites• Must invade your cells • Hijack organelles to reproduce itself
• Will antibiotics work against viruses?
NO
Viruses
Smallpox
InfluenzaEbola
Bacteriophage
Prions• Prions are misshaped proteins • When they encounter their normal counterparts, prions cause
them to refold and form into new prions, which then clump together
• Cause holes to form in the brain, giving it a spongy appearance• Cluster in spinal tissue and saliva• Mad cow disease, scrapie, Creutzfeldt-Jakob disease, kuru
Prions• No current treatment, is
100% fatal• Decontamination very
difficult• Survives bleach, heat,
concentrated bases and acids, UV
• Contamination at USAMC resulted in disposal of $300,000 worth of equipment