Antibiotics 1

Question 1

Cell wall of bacteria is made up of…

Answer 1

Peptidoglycan

Question 2

Macromolecule composed of peptides and sugars that provide a rigid support structure only found in bacteria

Answer 2

Peptidoglycan

Question 3

Lipopolysaccharide (LPS)
Makes up which membrane?
Which kind of bacteria?
Consists of (2)?

Answer 3

Makes up the outer membrane of gram (-) bacteria cell wall and consists of phospholipids and polysaccharides

Question 4

4 features of gram (-) bacteria that influence antibiotics

Answer 4

LPS
Lipid Bilayer
Hydrophilic pores
Nutrient receptors

Question 5

How does LPS inhibit antibiotics?

Answer 5

Retards or prevents penetration of bulky, high MW antibiotics such as erythromycin

Question 6

How does the lipid bilayer inhibit antibiotic action?

Answer 6

Penetration of water-soluble drugs is severely hindered

Question 7

How do hydrophilic pores influence antibiotic action?

Answer 7

The pores actually allow penetration of water-soluble molecules up to 650 Daltons (like sulfonamides) but that’s it…nothing bigger

Question 8

3 factors of gram + bacteria that influence antibiotic action

Answer 8

Teichoic and teichuronic acid
Lipid bilayer of cytoplasmic membrane
Nutrient transporters

Question 9

How do teichoic and teichuronic acid influence antibiotics on gram + bacteria?

Answer 9

The strong anionic action affects rate of penetrations. They literally repel drugs with negative charge

Question 10

How does the bilayer affect antibiotics on gram + bacteria?

Answer 10

Same thing…Penetration of water-soluble drugs is inhibited

Question 11

How does the nutrient transporter work on either bacteria?

Answer 11

If a drug is similar to the nutrient normally transported, then it will go through. Otherwise, not so much

Question 12

Bactericidal

Answer 12

Agent that will kill the bacteria. Once the organism is exposed to the drug…it dies…like real quick

Question 13

Bacteriostatic

Answer 13

Agent will inhibit bacterial growth but will not kill it. Therapeutic success is dependent on host defense
If the drug is removed, the bacteria will grow again

Question 14

Pre-emptive therapy

Answer 14

Treatment of high-risk patients that are infected but asymptomatic

Question 15

Empirical therapy

Answer 15

Treatment of symptomatic patient without further testing or confirmation of the organism

Question 16

Definitive therapy

Answer 16

Organism is identifed

Question 17

Suppressive therapy

Answer 17

Low does therapy used as secondary prophylaxis

Question 18

6 ways resistance develops

Answer 18

1. Reduced drug entry into organism
2. Increased drug export from organism
3. Expression of enzymes by organism that destroy drug
4. Changes in expression of enzymes that activate the drug (pro-drug)
5. Impaired drug binding to the original target
6. Development of new/different pathways what are not inhibited by the drug

Question 19

ESKAPE bacteria

Answer 19

Enterococcus facecium
Staph aureus
Klebsiella pneumonia
Acinetobacter baumannii
Psuedomonas aeruginosa
Enterobacter species

Question 20

Daptomycin resistance mechanism

Answer 20

Gene mutation of mprF that results in overall increase in net positive charge of inner and outer membranes that repel antibiotics with cationic charge

Question 21

Tetracycline resistance mechanism

Answer 21

Overexpression of an efflux pump

Question 22

Metronidazole resistance mechanism

Answer 22

Metronidazole needs to be reduced to generate ROS. Mutation in the rdxA gene alters or decreases activation of the drug

Question 23

Streptomycin resistance mechanism

Answer 23

Aminoglycoside-modifying enzymes chemically modify the antibiotic and alter the binding of the drug to its target

Question 24

Amoxicillin resistance mechanism

Answer 24

Expression of beta-lactamases

Question 25

TMP-SMX resistance mechanism

Answer 25

Expression of the drug INSENSITIVE enzymes dihydropteroate synthase and dihydrofolate reductase

Question 26

Vancomycin resistance mechanism

Answer 26

Substitution on the peptidoglycan stem so that the agent can no longer bind to its target