Antimicrobial resistance

Question 1

What is the cell wall like of antibiotic free cells?

Answer 1

Without beta-lactam antibiotic, transpeptidase (penicillin binding proteins) catalyze the cross links between glycan changes in the peptidoglycan
Results in covalent bonds between peptide and sugar chains → create rigid shell tha protect cell from osmotic force that result in cell rupture

Question 2

What is the mechanism of resistance in Beta-Lactams?

Answer 2

Beta-lactam antibiotics are similar to natural peptidoglycan subunits (D-ala-D-ala) that are substrate for trsnpeptidases
These antibiotics binds strongly to transpeptidase and stop cell wall synthesis

Question 3

How can penicillin be converted into synthetic beta-lactams?

Answer 3

Beta- lactam antibiotics contain same core 4 member beta-lactam ring, minic the shape of terminal D-ala-Dala peptide sequence that is substrate for transpeptidase
Chemical modifications of penicillins led to development of synthetic beta-lactams, and greater resistance to beta-lactamases and other pharmacokinetics

Question 4

What are the general resistance mechanisms of beta-lactams?

Answer 4

Penetration → intracellular bacteria are resistant to beta-lactams if they are mammalian cell
Porins→ g- bacteria are resistant to beta-lactams since the outer membrane protects peptidoglycan
Pumps→ g- can express ABC trsnporters to pump antibiotics out of the cell
Peptidoglycan is absent → some bacteria lack cell wall

Question 5

What are specific resistance mechanisms for Beta-lactams?

Answer 5

penicillinases→ some bacteria can make beta-lactamases that degrade beta-lactam antibiotics before they reach th cell
PBPs→ bacteria express mutated transpeptidases that still have enzymatic activity for cell wall synthesis but don’t bind to bl antibiotics

Question 6

Where are antibiotics used ?

Answer 6

Humand medicine, agricultural production, food processing

Question 7

What antibiotics has first used to increase the rate of weight gain in poultry (antibiotics growht promoter (AGPs)?

Answer 7

Aureomycin

Question 8

What is fed to chickens? Cattle?

Answer 8

Chicken- bacitracin and ionophores
Beef- ionophores
Dairy- ceftiofur to reduce mastitis

Question 9

What are the main uses of antibiotics in agriculture?

Answer 9

Increasing growth rate and feed efficiency. It reduces death and reduces instances of infections

Question 10

What are the 4 Antimicrobial Categories in Canada?

Answer 10

Very high importance (I)
Essential for treatment of serious infection with limited alternatives
High importance (II)
Treat variety of serious infections, general alternatives available
Medium importance (III)
Treatment of bacterial infection where alternatives are generally available
Low importance (IV)
Not used in human medicine

Question 11

Which level of AMR have specific warnings?

Answer 11

I,II,III

Question 12

Give 1 example of each level AMR

Answer 12

Lvl I
Cephalosporins- Ceftifur
Lvl II
Cephalosporins
Penicillins
Lvl III
Bacitracins
Tetracyclines
Lvl Iv
Ionophores
Flavophospholipids

Question 13

What is the effectiveness of categorization?

Answer 13

CI (Ceftiofur) is used in dairy and CIII and IV antibiotics use din poutlry
Semi-synthetic antibiotics approved to treat MRSA in humans → Virginiamycin use in broiler chicken and swine-> acetyltransferases have resistance to Synercid
Banned Ceftiofur in 2014 due to increase salmonella nd Ecoli that were resistant to 3rd generation cephalosporins

Question 14

What are some possible replacements for antibiotics?

Answer 14

Improved hygiene
Bacteriophages
Probiotics
Antibiotics

Question 15

Give some examples of Anti-adherence/biofilm interactions?

Answer 15

Competitive binding and anti-adhesive
Modulation of gene expression
Biofilm disruption

Question 16

Give some examples of growth inhibition for bacterial interactions? All lead to membrane disruption

Answer 16

Organic acids, 
H2O2
Biosurfactans
Phenolic acids
Secreted enzymes