Antibiotics - 33 Flashcards
What does ‘selective toxicity’ mean
A toxin that kills microbial cells but not the hosts cells
Why did selective toxicity come about
Early medicine used highly toxic ‘medicine’ to treat infectious diseases. These often turned out to me more harmful than the disease
What did methylene blue do
Stained microbes better than host cells
What is penicillin
Chemical produced by a fungus that inhibits bacterial growth. First important selective toxin (antibiotic)
How does penicillin work
It inhibits the formation of the bacterial wall by inhibiting the enzyme that binds it together (peptidoglycan crosslinks). Causes the cell to lyse (fall apart)
What kind of bacteria is penicillin most effective for
Gram positive (thick cell wall)
What are the 5 main bacterial cell components targeted by different antibiotics
Inhibition of cell wall synthesis Inhibition of protein synthesis Disruption of cytoplasmic membrane Inhibition of general metabolic pathways Inhibition of DNA or RNA synthesis
What is a special case of antibiotics targeting components of bacteria cells
Inhibition of pathogens attachment or entry into host cell
How does antibiotic resistance occur
Bacteria with certain mutations may be able to survive antibiotics. Due to natural selection these individuals reproduce more bacteria resistant to the antibiotic
What is an example of a bacterial mutation that leads to antibiotic resistance
Beta Lactamase - produces an enzyme that is used to destroy penicillin (breaks apart Beta lactam ring)
What happens when bacteria no longer under the pressure of the antibiotic
Sometimes mutated bacteria may revert back as selection pressure no longer needs that mutation to survive
What are the 2 types of antibiotic resistance gene transfer
Vertical - Producing daughter cells
Horizontal - Giving mutation to other bacteria
What are the 4 basic ways we can reduce the development of antibiotic resistance
Decrease antibiotic use
Improve diagnostics
Identify new targets
Combination therapies
How can we decrease antibiotic use
Improve hygiene to reduce infections
Restrict use in agriculture
How can improving diagnostics help
Identifying resistant bacteria can make treatment more effective and reduce outbreaks
