抗生素使用的优缺点（英文PPT）AntibioticsPPT.pptVIP

Antibiotics D. Crowley, 2009 Antibiotics To understand how antibiotics work and the advantages and disadvantages associated with them 2018年2月1日 Antibiotics Antibiotics are substances that kill bacteria or stop their growth (often targeting the bacteria’s cell capsule) They do not work against viruses – it is difficult to develop drugs that kill viruses without also damaging the body’s tissues Antibiotics Antibiotic Target Penicillin Breaks down cell walls Erythromycin Inhibits protein synthesis Neomycin Inhibits protein synthesis Vancomycin Inhibits protein synthesis Ciprofloxacin Inhibits DNA replication Penicillin The first antibiotic (penicillin) was discovered in 1928 by Alexander Fleming He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould Since the discovery of penicillin, many other antibiotics have been discovered or developed – most antibiotics used in medicine have been altered chemically to make them more effective and safer for humans Resistance Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new resistant ‘strains’... Bacteria Antibiotic Variation – some strains of bacteria are resistant Competition – the non-resistant bacteria are killed by the penicillin Survival of the fittest – the resistant bacteria survive Reproduction – the resistant bacteria reproduce and pass on their adaptations to their offspring Bacterial Growth Using the agar plates spread bacteria evenly over them Place some antibiotic disks randomly onto the culture (ensure you note which antibiotic plate is which)! Which antibiotic is the best? Which antibiotic are the bacteria most resistant to? A B C D E Bacterial Growth Using discs on agar covered with bacteria – this technique is used in hospitals on samples of urine, blood and stools to work out which antibiotic to use The antibiotic disc which has the caused the widest circle in the bacterial plate