week 5

Question 1

selective toxicity

Answer 1

ability of a drug to kill or inhibit pathogen while damaging host as little as possible

Question 2

therapeutic dose

Answer 2

drug level required for clincial treatment

Question 3

toxic dose

Answer 3

drug level at which drug becomes too toxic for patient

Question 4

therapeutic index

Answer 4

ratio of toxic dose to therapeutic dose
- want this to be as large as possible

Question 5

side effects

Answer 5

undesirable effects of drug on host cells

Question 6

narrow spectrum drugs

Answer 6

attack a few specific organsims

Question 7

broad spectrum drugs

Answer 7

attack a wide range of organisms

Question 8

Minimal inhibitory concentration (MIC)

Answer 8

lowest concentration of drug that inhibits growth of pathogen

Question 9

Minimal lethal concentration (MLC)

Answer 9

lowest concentration of drug that kills pathogen

Question 10

how to measure MIC?

Answer 10

dilution susceptibility test- drug with lowest concentration showing no growth

Question 11

what does MIC stand for

Answer 11

minimal inhibitory concentration

Question 12

Disk diffusion test

Answer 12

measures different disks with antimicrobial agents on agar
- zones of inhibition = effective antibiotic

Question 13

What are the targets of antibiotics

Answer 13

inhibitors of cell wall synthesis
protein synthesis inhibitors
metabolic antagonists
nucleic acid synthesis inhibition

Question 14

Penicillin

Answer 14

• effective on gram positive bacteria
• blocks the enzyme that catalyzes transpeptidation
  (formation of cross links in peptidoglycan)
  prevents the synthesis of complete cell walls= cell lysis

Question 15

cephalosporins

Answer 15

similar to penicillin
- broad spectrum (negative + positive)

Question 16

Vancomycin and Teicoplanin

Answer 16

binds to peptidoglycan structure
gram positive antibiotic
- inhibit cell wall synthesis

Question 17

Aminoglycosides

Answer 17

antibacterial against gram negative aerobic and facultative anaerobic bacteria

• binds to 30S ribosomes, interferes with protein synthesis by inhibiting the process and causing the misreading of the mRNA

Question 18

Tetracyclines

Answer 18

four ring structure with varying side chains attached
- broad spectrum, bacteriostatic
- inhibits binding of aminoacyl - tRNA molecules to A site of ribosome

Question 19

Macrolides

Answer 19

broad spectrum, bacteriostatic
binds to 23S rRNA and 50S ribosomal subunits
- inhibits peptide chain elongation

Question 20

Trimethoprim

Answer 20

broad spectrum
interferes with folic acid production

Question 21

sulfa drugs

Answer 21

selectively toxic due to competitive inhibition of folic acid synthesis enzymes
- bacteriostatic

Question 22

Quinolones

Answer 22

-broad spectrum
-acts by inhibiting bacterial DNA gyrase and topoisomerase II
- bactericidal

Question 23

Lipopeptides

Answer 23

very effective against gram positive organisms
- inserts into membrane near phoshatidylglycerol, then aggregates, changing membtrane curvature and allowing little holes to form
this depolarizes membrane