Antibiotics Flashcards
What is selective toxicity?
A chemical ‘magic bullet’ that kills microbial cells but not the host cell
Created by Paul Ehrlich in 1909
First selective antibiotic : Salvarsan or compound 606
What is Penicillin?
Penicillin targets normal formation of bacterial cell walls and breaks layers between peptidoglycan inhibiting the formation of peptidoglycan cross links
Observed by Alexander Fleming in 1928
What is the zone of inhibition?
Zone where bacterial growth is inhibited - region where there is no bacterial growth on plate
Used to measure antibiotic susceptibility in the Kirby-Bauer test
What bacterial cell components can different classes of antibiotics target?
Inhibition of wall synthesis
Inhibition of protein synthesis
Disruption of cytoplasmic membranes
Inhibition of general metabolic pathway
Inhibition of DNA or RNA synthesis
Inhibition of pathogens attachment to entry into host cell
How can bacteria become resistant to antibiotics?
Mutation occurs in the bacteria which gives it antibiotic resistance allowing it to survive and reproduce passing on the resistant trait
What is Beta Lactamase?
An enzyme produced by bacteria and used to destroy penicillin
Beta lactamase breaks bond in B-lactim ring of penicillin to disable the molecule allowing it to resist effects of penicillin and other antibiotics
Vertical gene transfer process for antibiotic resistance
Bacteria gains resistance mutation
Some will survive against antibiotic
Bacteria will multiply/reproduce, passing on the trait
Bacteria populations that inherit the gene will survive
Horizontal gene transfer process for antibiotic resistance
Some bacteria gain resistance by a curing genes from external sources occurring through transformation (most common), transduction and conjugation
How can we reduce the spread of antibiotic resistance?
Decrease antibiotic utilisation
Improve diagnostics
Identify new targets
Combination therapies
How can we reduce the spread of antibiotic resistance through decreasing antibiotic utilisation?
Reduce infections and outbreaks through improved hygiene and infrastructure; restrict use of antibiotics in agriculture
How can we reduce the spread of antibiotic resistance through improving diagnoses?
Use new methods to identify resistant bacteria can make treatment more effective, reduce outbreaks
Wait till diagnosis confirmed before suppling patient with antibiotics
How can we reduce the spread of antibiotic resistance through identifying new targets?
Some cellular pathways are harder for bacteria to bypass or modify, making them ideal targets for new antibiotics
How can we reduce the spread of antibiotic resistance through combination therapies?
Traditional antibiotics can be combined with molecules that block resistance mechanisms
