Antimicrobial Suscptibility Flashcards
What are the main targets for antibacterial drugs?
1) Cell wall synthesis
2) Nucleic acid synthesis
3) Protein synthesis
How can the susceptibility to antibiotics be measured?
1) Broth dilution method (Gold standard)
2) Disk diffusion method
3) Molecular methods like PCR
What are the bacterial mechanisms of antimicrobial resistance?
1) Modification of antibiotic drug (destruction or modification)
2) Modification of drug target
3) Decreased permeability in the plasma membrane
4) Elimination of drug by active efflux through efflux pumps in the membrane
5) Target site protection
6) Target overproduction
How can modification of antibiotic drugs be performed?
Modification may happen by enzymatic hydrolysis of the antibiotic, or by other mechanisms.
Many different enzymes work in this process, but B-lactamases are the most important by splitting the betalaktam ring of betalactam antibiotics.
How can modification of drug target occur?
1) By random mutation.
Relevant for several drugs, including kinolones, macrolides and aminoglycosides
2) By horisontal gene transfer
How is the permeability of the plasma membrane decreased?
1) Reduced passage of drug through membrane pores due to either reduction in number of pores or modification of pores.
2) Reduced uptake of drug due to thickened cell wall
3) Biofilm
What are the causes of antibiotic resistance?
1) Over-prescribing of antibiotics
2) Patients not taking antibiotics are prescribed
3) Unnecessary antibiotics used in agriculture
4) Poor infection control in hospitals and clinics
5) Poor hygiene and sanitation practices
6) Lack of rapid laboratory tests
7) International travel
What are the consequences of antibiotic resistance?
1) Increased risk of treatment failure
2) Some types of treatment rely on effective antibiotics
3) Have to use alternative drugs which may have more side effects, be more expensive, and be less effective
How can we combat antibiotic resistance?
1) Improve awareness and understanding of AMR (antimicrobial resistance)
2) Strengthen knowledge and evidence through surveillance and research
3) Reduce incidence of infection through effective infection control measures
4) Optimize the use of antimicrobial drugs in human and animal health
5) Develope the economic case for sustainable investment: new medicines, diagnostic tools, vaccines, and other interventions
By which processes are AMR genes spread?
By horisontal gene transfer.
1) Transduction
2) Conjugation
3) Transformation
What is intrinsic resistance?
That is the resistance exhibited due to the inherent properties of the bacterium.
Examples of intrinsic resistance include the glycopeptide resistance exhibited by Gram-negative bacteria due to the impermeability of the outer membrane present in the Gram-negative bacterial cell envelope.
What is acquired resistance?
That is the resistance exhibited when a previously sensitive bacterium acquires a resistance mechanism by either a mutation of the acquisition of new genetic material from an exogenous source (horizontal gene transfer)
What is adaptive resistance?
It is the resistance to one or more antibiotics induced by a specific environmental signal (e.g., stress, growth state, pH, concentrations of ions, nutrient conditions, sub-inhibitory levels of antibiotics). This type of resistance is transient.
It seems to be a result of modulations in gene expression as a response to environmental changes.
