Download Antibiotics, Viruses, and Prions

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
Ebola
Influenza
Smallpox
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