Antibiotics 1

Question 1

Describe the nomenclature of bacteria

Answer 1

Named by common characteristics. Also named by genus and species.

Question 2

what is the cell wall made of

Answer 2

Peptidoglycan

Question 3

What is peptidoglycan

Answer 3

a macromolecule composed of peptides and sugars that provide a rigid support structure found only in bacteria. Thick wall of peptidoglycan is gram +

Question 4

What is lipopolysaccharide

Answer 4

makes outer membrane strctr of gram - bacteria cell wall and consists of phospholipid and polysaccharides.

Question 5

What is cytoplasmic membrane

Answer 5

similar in strctr to eukaryotic cell membrane(except sterols)

Question 6

What is LPS’s effect on antibiotics

Answer 6

retards or prevents penetration of bulky, high molecular weight antibiotics like erythromycin

Question 7

Lipid bilayer of cytoplasmic membrane

Answer 7

penetration of water soluble drugs is severely hindered

Question 8

Hydrophillic pores

Answer 8

allow penetration of water soluble molecules up to 650 Daltons, such as sulfonamides.

Question 9

Nutrient receptor prtns on outer membrane

Answer 9

Agents structurally related to nutrients (sideromycins) utilize these natural receptors

Question 10

Teichoic and Teichuronic acid

Answer 10

strong anionic character of these polymers may affect rate of penetration

Question 11

What is selective toxicity

Answer 11

kill or impair growth of specific target organisms w/o harming host

Question 12

What is a narrow spectrum antibiotic

Answer 12

drug that has effect on one type of species or organism. Use if organism known

Question 13

Broad spectrum?

Answer 13

drug has effect on a wide variety of organisms. Use if causative agent unknown. Tetracycline can be used to treat both gram negative and gram positive.

Question 14

Difference bw prophylactic and pre emptive therapy?

Answer 14

Prophylactic is treatment in absence of infection in order to prevent disease. Pre emprive is treatment of high risk pts that have become infected but are asymptomatic

Question 15

Empirical therapy

Answer 15

treatment of symptomatic pt w/o further testing or confirmation of organism

Question 16

Definitive therapy

Answer 16

treatment once pathogenic org has been identified and appropriate drug identified

Question 17

Suppressive therapy

Answer 17

generally a low dose therapy used as a secondary prophylaxis. Problem that caused initial infection is likely still present.

Question 18

What are the “ESKAPE” organisms

Answer 18

commonly drug resistance bugs-Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, Enterobacter species

Question 19

Resistance in daptomycin

Answer 19

Gene mutation changes charge of membrane, making net postive at outer and inner membrane. Repels Ab with positive charge

Question 20

Tetracycline

Answer 20

Orgs express efflux pump

Question 21

Metronidazole

Answer 21

Must be reduced to activate drug. Mutation in rdxA gene alters or decreases activation of the drug.

Question 22

Aminoglycosides such as streptomycin

Answer 22

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

Question 23

Amoxicillin

Answer 23

B lactamase can hydrolyze the lactam ring of amoxicillin (as well as other penicillins and cephalosporins) and render the compound ineffective

Question 24

Trimethoprim and sulfonamides

Answer 24

Expression of drug insensitive enzymes dihydropteroate synthase and dihydrofolate reductase

Question 25

Vancoymycin

Answer 25

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