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 Influenza Ebola 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