Antibiotics & microbes Flashcards
(31 cards)
used:
-mould
-herbs
-heating
pre-antibiotics
what do Louis Pasteur discover
- microbes for spoiled wine and sour milk
- product of one microbe may inhibit another
what did Dubos do?
- isolated tyrothricin
- cured infection in mice
- too toxic for internal organs & tissue
- external use only
what did Ehrlich do?
- tested 600 arsenic compounds
- arsphenamine - effective against syphilis
what did Domagk do/
- prontosil - effective against staphylococci in mice
- a sulphanilamide
what did Flemming do?
- discovered penicillin
- saved 200M lives
substances that will damage pathogens but do no harm to host cells
- secondary metabolites
- microbes or extracts
- natural or synthetic
antibiotics
-bacteria, filamentous
- source of 75% described antibiotics
- high [G&C] in DNA
- full genome known
streptomyces
- 20% all antibiotics
- chemotherapeutic antibiotics
- filamentous, spore-forming moulds
fungi or moulds
- 5% all antibiotics
- antibiotics as polypeptides
true bacteria
sources of antibiotics
- soil
- sewage
- excreta
- rotten food
- sea
- hospital isolates
preparation of an antibiotic
1) sample, grow & isolate microbes
2) test isolates as antimicrobials
3) synthetic
antibiotics testing & safety
MIC = minimum inhibitory concentration
- prepare liquid media, add antibiotics
- inoculate w/ test microbes
- incubate
pathogen growth, no inhibition
turbid culture
no pathogen growth at lowest dose
clear culture
microbial prepare and test
identify genes in microbes
gene mutation to enhance yield
- X-ray
- UV radiation
- chemicals
gene modification & amplification
extraction & purification
test for potency, toxicity, safety & efficacy
how antibiotics work
ions & metabolites inside > outside
- generate energy
- molecular synthesis
- growth & division
more osmotic pressure inside
- cell membrane = delicate, covered w/ rigid cell wall
repeated peptidoglycan
- glycan
- tetra-peptide
antibiotic cell wall
five major antibiotic groups based on target site for attacks
- cell wall = penicillin
- cell membrane = polymyxin
- cell metabolism = sulphonamide
- protein synthesis = streptomycin
- nucleic acid replication = actinomycine
2 antimicrobial classifications
- bactericidal
- bacteriostatic
- kill/dissolve pathogen by breaking cell wall
bactericidal antimicrobial
- suppress or stop bacterial growth
- rely on host defence = if treatment stops, infection reoccurs
- bactericidal if dose increased
bacteriostatic
4 antibiotic examples
- B-Lactam
- ahminoglycosides
- macrolides
- sulphonamide & trimethoprim
- penicillin like
- lactam molecule w/ amide bond within 4 member ring
- involves an amide N & carbonyl carbon
B-Lactam
