PID: Antimicrobial resistance Flashcards
What mechanisms do bacteria acquire AMR through?
Target protection, Target Modification, Drug trapping, Enzymatic degradation, Active efflux, Change in membrane permeability
Explain target protection of AMR in bacteria
Bacteria will produce a substance that will protect the target, no binding can occur between the bacteria and antimicrobial
Explain target modification of AMR in bacteria
Alteration of bacterial proteins that are antimicrobial targets so they will no longer bind to the antimicrobial
Explain drug trapping of AMR in bacteria
The bacteria can produce another compound that will cause the antimicrobial to have a higher affinity for than the target and trap the drug.
Explain enzymatic degradation of AMR in bacteria
Bacteria will secrete enzymes that will inactivate or neutralize the ability of the antibiotic
Ex: penicillinase acting on penicillin.
Explain active efflux of AMR in bacteria
Will cause a reduction of intracellular antibiotic concentration through efflux pumps.
Explain changes in membrane permeability of AMR in bacteria
Changes in membrane permeability to antibiotics. This will reduce antibacterial uptake into the bacterial cell.
How do AMR genes/mutations confer resistance?
They acquire resistance through mutation at the antimicrobial target gene
It can also be acquired through horizontal gene transfer
What are the 3 mechanisms of gene transfer?
Transformation: uptake of free DNA
Transduction: transfer mediated by phage delivery
Conjugation: cell to cell contact
What makes MRSA and MRSP resistant to beta lactams?
They have an acquired gene mega that has penicillin binding proteins that create a low affinity for beta lactams. It allows bacteria to synthesize a cell wall without interference from penicillins.
What is the effect of MRSA on public health?
MRSA occurs mainly in pigs but infects companion animals and dairy cows. Can be harmful to humans by indirect exposure from a farmer where it eventually can make its way into the healthcare environment.
What is the effect of MRSP on public health?
MRSP occurs mainly in dogs. Along with MRSA, they have a low risk of food transmission. Difficult to treat because it may be resistant to all antibiotics licensed for veterinary use. Humans can act as vectors for MRSP.
What is ESBL? How does it work?
An enzyme produced by gram negative bacteria (E. coli) with an extended spectrum of beta lactams it can be effective against (beta-lactam resistance)
It will hydrolyze or inactivate most beta lactams except carbapenems
Can be susceptible to b-lactamase inhibitors such as clavulanic acid
What are the classes of ESBL? And what animals does it occur in?
Occurs in all animal species and has risk of transmission in food.
Three classes: CTX-M, SHV, TEM. CTX-M is most common
False class: CMY-2. False since it is resistant to inhibitors.
