Summary Antibiotics

Question 1

How do we inhibit growth of gram positive bacteria (Staphylococcus, Streptococcus)

Answer 1

• B-lactams

- block PBP from binding to D-Ala substrate by having a B-lactam ring that looks like the substrate D-Ala

Question 2

How do gram positive bacteria (Staphylococcus, Streptococcus) Develop resistance to B-lactam drugs

Answer 2

Altered PBPs

-prevent binding of B-lactam antibiotics via modification of antibiotic target

Question 3

How do scientist overcome bacterial resistance to B-lactams in gram positive bacteria

Answer 3

you can’t….if it is B-lactam resistant try a different drug with a different mechanism

Question 4

How do we inhibit growth of gram negative bacteria (eg E coli, Psuedomonas)

Answer 4

B-lactam drug

-block PBP from binding to D-Ala substrate by having a B-lactam ring that looks like the substrate D-Ala

Question 5

How do gram negative bacteria develop resistance to antibiotics

Answer 5

B-lactamses that break the B-lactam ring of the antibiotic

Question 6

How do scientist overcome bacterial resistance to B lactams (via B lactamases) in gram negative bacteria

Answer 6

B-lactamase inhibitor

not super effective as an antibiotic as its own, bt is often given with a B-lactam drug.

SO you prescribe a B-lactam to inhibit peptidoglycan synthesis and kill bacteria, and then you prescribe a B-lactamase to overcome bacteria resistacne to the B-lactam

Question 7

Antibiotics

Answer 7

Small molecules that inhibit specific cellular processes in
bacterial cells and exhibit toxic effects on bacteria, but not on humans
– selective toxicity

Question 8

Antibiotic properties:

Answer 8

Bactericidal vs bacteriostatic; narrow vs broad spectrum

Question 9

Adverse effects

Answer 9

Antibiotic-associated diarrhea, antibiotic resistance
• Resistance is inevitable: Antibiotic use selects for emergence of
resistant bacteria; resistance traits can be passed between bacteria
on mobile genetic elements

Question 10

3 basic mechanisms of antibiotic resistance:

Answer 10

-modification of the
antibiotic, 
-modification of the antibiotic target, or 
-reduction in antibiotic
concentration

Question 11

B-lactam antibiotics target

Answer 11

cell wall biosynthesis by preventing PBPs from crosslinking peptidoglycan

Question 12

Bacterial resistance to

B-lactams is mediated by

Answer 12

enzymes that cleave
the antibiotic (B-lactamases) or by modifications in PBPs that prevent binding of antibiotic

Question 13

How do we use B-lactamase inhibitors

Answer 13

B-lactamase inhibitors can be used in combination with

B-lactams to prevent cleavage of the antibiotic by B-lactamases