Exam 1 Mon 1 27 14 picture ID Q A Friday TBA bring explanations TODAY 1 Archae Bacteria Qs 2 Antibiotic resistance Background case Qs PART IV Apply to Evolution Antibiotics Natural source several species of bacteria and fungi Alexander Fleming discovered activity of antibiotics by accident in 1928 Penicillium mold produces penicillin that kills bacteria Awarded Nobel Prize in 1945 Growth of bacteria Staphylococcus aureus is inhibited in the area surrounding the invading penicillin secreting Penicillium mold colony How Penicillin Works Rod shaped bacteria Membrane cell wall capsule Cell walls made of peptidoglycan scaffold Asexual reproduction have to replicate really fast Attack the cell wall assembly of pathogenic disease causing bacteria As a result no more cell walls can be assembled and cells can t divide Penicillin inhibits peptidoglycan synthesis which prokaryotes should thus be most vulnerable to penicillin A all bacteria equally D gram negative bacteria B Archae E gram positive bacteria C Eubacteria Gram negative has inner and outer membrane outer is over peptidoglycan layer Gram positive only has inner membrane under peptidoglycan layer How vancomycin works Doesn t work with enzyme only it attacks peptidoglycan Enzyme cannot assemble the scaffold Can be vancomycin sensitive or resistant Cells walls are not the only way of attack 5 ways antibiotics can work Inhibition of cell wall synthesis penicillin cephalosporin vancomycin bacitracin Injury to plasma membrane polymyxin B mystatin amphotericin B miconazole Inhibition of synthesis of essential metabolites trimethoprim Inhibition of nucleic acid replication and transcription rifampin quinolones Inhibition of protein synthesis streptomycin erythromycin tetracycline About 70 of bacteria that cause infections in hospitals are resistant to at least one of the drugs most commonly used to treat infections Nearly 2 million patients get an infection in a hospital each year o 90 000 die as a result Microbes organisms too small to be seen by unaided eye bacteria protists archae and fungi Why are viruses not included here Antibiotic resistance How and why 1 Review evolution by natural selection 2 Apply to evolution of antibiotic resistance Vertical gene transfer binary fission Main points to mention in letter Antibiotics Genes Mutations Adaptations DNA changes Resistance to antibiotics Natural selection Gene transfer horizontal Taken to hospital with serious bacterial infection TO ensure you are treated w most effective antibiotic your doctor culture your bacteria A pure culture can be tested for antibiotic resistance by evenly swabbing it over an agar plate and pressing discs of diff antibiotics After a period of incubation bacterial growth sensitivity or resistance to antibiotics can be determined by measuring the zone that forms around the discs Antibiotic disc with less clear space around it is the most resistant because none of the bacteria is being inhibited antibiotic disc with the most clear space around it is the least resistant because Clicker You feel better after taking your antibiotic pills for 6 days The infection seems to be gone and since the antibiotics give you an upset stomach What should you do A stop right away C take them for 10 days B take them for another day D take them until they are gone Bacteria could not be completely gone Last bacteria left would be the most resistant Not finishing regimen can contribute to resistance Taking it for viruses can also lead to resistance as well Why does it happen so fast Our part selection for resistant variants Triclosan antibiotic Implicated in causing damage in hormonal system Breeding resistant bacteria in your environment