L9_Antimicrobial resistance & sustainable healthcare Flashcards
What is the difference between antibiotic resistance and anti-microbial resistance?
- antibiotic resistance = when bacteria are no longer affected by antibiotics.
- anti-microbial resistance = microorganisms (bac, fungi, parasites) aren’t affected by antimicrobials.
How many people are killed from antibiotic resistance infections every year?
- 700,000.
What is intrinsic/natural resistance? (3)
- resistant to the antibody bc they lack or have a different drug target.
- they may produce enzymes that deactivate the drug.
- have reduced drug uptake.
- some bacteria can sequester antibiotic inside a cell so they are not active.
What is acquired resistance?
- when bacterium was previously susceptible to the antibiotic but develops resistance either through; a mutation and/or horizontal gene transfer.
What is horizontal gene transfer?
- when bacteria are able to pick up DNA from their environment and incorporate it into their own genome.
- or when they can share resistance genes with other bacteria.
What is veritcal gene transfer?
- normal binary fission.
- parent bacterial cell gives rise to two identical daughter cells.
- this leads to clonal expansion.
What is bacterial transformation?
- a type of horizontal gene transfer.
- donor bacterium will release DNA into the environment.
- ‘competent’ recipient bacterial cells can pick up the DNA from their environment and incorporate it into their own genome.
What is bacterial transduction?
- this is when viruses which infect bacteria (bacteriophage) during the lysogenic life cycle, they integrate into the bacterial host genome.
- during the lytic phase, the bacteriophage packages up its genome and goes on to affect a new bacterial host.
- during this lytic phase, the bacteriophage may also take a bit of the genome encoding antibiotic resistance.
What is direct selection for resistance?
- bacterium is exposed to antibiotic.
- bacterium becomes resistant to antibiotic.
What is co-selection for resistance?
- bacterium is exposed to antibiotic A.
- but it becomes resistant to antibiotic A, B and C.
Out of gram-positive and gram-negative bacteria, which are easier to treat with antibiotics and why?
- gram-positive bacteria are easier to treat.
- bc they are more permeable to antibiotics due to the lack of an outer membrane (as present on gram-negative bacteria).
MRSA:
a) Type of bacteria.
b) As a commensal bacteria, where can it be found?
c) Why might it be found in diabetes sufferers?
a) facultative anaerobic bacteria (Staph aureus).
b) Primarily nasal.
c) bc its an OI.
Which gene in MSRA confers its resistance to penicillin?
- MecA gene.
- encodes for a penicillin binding protein 2a (PBP2a).
- PBPs are trans-peptidases required in PDG synthesis for cell wall synthesis.
- Usually β-lactams can bind PBPs, which prevents cell wall synthesis, thus killing the bacterium.
- however, β-lactams have low affinity for PBP2a, thus they are unable to impair bacterial cell wall synthesis.
Between MRSA and E. Coli, which bacterial species are more likely to cause blood infections? And why?
- E. Coli.
- E. Coli is a gram-negative bacteria.
What are extended-spectrum β-lactamases (ESBLs)?
- a method by which bacteria confer their resistance to β-lactam antibiotics.
- bacteria produce the enzyme ESBL, which cleave the β-lactam ring in β-lactam antibiotics.
Some bacteria produce EBSLs allowing them to gain resistance against β-lactam antibiotics. However, they are still susceptible to a type of antibiotics? Name this class of antibiotics.
- carbapenems.
Some bacteria are resistant to carbapenems. Describe a mechanism via which this resistance occurs.
- some bacteria have the enzyme carbapenemases.
- they break down the antibiotic.
- e.g. the NDM-1 gene is found on plasmids that can easily move between bacteria.
What is the Red Queen hypothesis?
- you have to keep running in order to stay in the same place.
What is phage therapy?
- an alternative to antibiotic therapy against bacteria.
- viruses can infect bacteria.
- during their lytic cycle, they can lyse bacteria and kill them.
- they can be designed to kill specific pathogens.
