Antibiotics and Chemotherapy

Question 1

Broad-spectrum

Answer 1

effective against many species

Question 2

Narrow-spectrum

Answer 2

Effective against few or single species

Question 3

Source of antibiotics

Answer 3

• most discovered as natural producs
• often modified by artificial means

Question 4

MIC

Answer 4

Minimum inhibitory concentration

lest amount of drug to block growth

Question 5

MBC

Answer 5

Minimum bacterial concentration

least amount of drug to kill every living thing present

Question 6

What test can you do to measure the MIC on a petri dish?

Answer 6

E-test strips, as they have a gradient of drug conentration

Question 7

Tube dilution assay

Answer 7

• dilution sereis of drug
• drop of bacteria in tube with drug
• see growth (not inhibited) and no growth (inhibited visible growth)
• minimum concentration with no visible growth is MIC
• take tube with no drug, and transfer drop of all no growth tubes and see what does or does not grow
• minimum cencentration where bacteria does not grow in drug-free tube is MBC

-MBC is higher concentration than MIC

Question 8

Examples of membrane-ative drugs

Answer 8

Polymyxin and Gramicidin

Question 9

What does Polymyxin and Gramicidin do?

Answer 9

bind to phospholipids and lipid A to disrupt membranes

Question 10

Nalidixic Acid

Answer 10

A subunit: Blocks nicking of DNA strands

Question 11

Novobiocin

Answer 11

B subunit: Blocks ATP hydrolysis

Question 12

Fluoroquinolones

Answer 12

• often given as broad-specrum antibiotics
• hits supercoiling

Question 13

Rifampin

Answer 13

• Binds to RNA polymerase
• Specific for bacteria
• Prevents elongation of transcript after initiation (not used commonly)
• useful drug against Mycobacterium tuberculosis

Question 14

What drugs target translation?

Answer 14

• Aminoglycosides
• Tetracycline – Blocks the A site
• Chloramphenicol – Binds 50S
• Erythromycin – 50S Subunit Near P Site

Question 15

Oxazolidinones

Answer 15

prevent formation of the 70S ribosome initiation complex

Question 16

Examples of Aminoglycosides

Answer 16

Streptomycin and Neomycin

Question 17

Aminoglycosides binds to

Answer 17

30S

Question 18

What does Tetracycline do?

Answer 18

• blocks the A site
• prevents tRNA from entering
• reversible
• bacteriostatic

Question 19

What does Chloramphenicol do?

Answer 19

• binds to 50S
• blocks peptide bond formation
• prevent peptidyl transfer reaction

Question 20

Macrolide example

Answer 20

Erythromycin

Question 21

Erythromycin function

Answer 21

• prevents translocation
• 50S subunit near P site

Question 22

An important carbon and hydrogen carrier

Answer 22

Tetrahydrofolate

Question 23

Sulfa drugs are associated with the the blocking of

Answer 23

Tetrahydrofolate acid

Question 24

Sulfa drug examples

Answer 24

Sulfanilamide and Trimethoprim

Question 25

Isoniazid

Answer 25

• Mycolic acid formation inhibited
• This is one of the main anti-tuberculosis drugs

Question 26

Fosphomycin

Answer 26

PEP Analog
- not used clinically due to toxicity

Question 27

What kind of bacteria have mycolic acid?

Answer 27

Acid fast bacteria

Question 28

Cross linking (peptidoglucan biosynthesis) is prevented by the

Answer 28

penecillins

Question 29

D-cycloserine

Answer 29

D-alanine analog
- blocks pentapeptide formation

Question 30

Lipid carrier inhibitors

Answer 30

• Vancomycin
• Bacitracin

Question 31

Vancomycin

Answer 31

Prevents release from lipid carrier
- last drug resort, very toxic

Question 32

Bacitracin

Answer 32

Blocks regeneration of carrier after release
- do not ingest

Question 33

How does cross linking work

Question 34

Beta-lactam drugs block

Answer 34

blocks transpeptidation

Question 35

Characteristic of Beta-lactam

Answer 35

4 member ring

Question 36

Examples of anti-fungal drugs

Answer 36

• Nystatin
• Imidazoles
• Amphotericin B
• Flucytosine
• Griseofulvin

Question 37

Nystatin

Answer 37

Targets the membrane

Question 38

Big difference between fungi and humans

Answer 38

humans - cholesterol
fungi - ergosterol

Question 39

Imidazoles

Answer 39

• Inhibit sterol (ergosterol) synthesis

Question 40

Amphotericin B

Question 41

Flucytosine

Question 42

Griseofulvin

Answer 42

• effective against ringworm
• prevents cell division

Question 43

Anti-virals

Answer 43

• Amantadine
• Acyclovir
• Ribavirin

Question 44

Amantadine

Answer 44

influenza A virus treatment (not as much anymore)

Question 45

Acyclovir

Answer 45

• Herpesviruses
• Nucleoside analog

Question 46

Ribavirin

Answer 46

blocks RNA synthesis

Question 47

Anti-HIV agents target and inhibit

Answer 47

Reverse transcriptase and protease

Question 48

Reverse transcriptase inhibitor

Answer 48

AZT

Question 49

Protease inhibitor

Answer 49

indinavir

Question 50

Antibiotics are ___ metabolites

Answer 50

secondary

Question 51

Bacteria ___ some antibiotics

Answer 51

secrete

Question 52

Bacteria can also make ___ to diable antibiotics

Answer 52

enzymes

Question 53

What is the main problem iwth antibiotic use?

Answer 53

antibiotics are overused

Question 54

Two main ways to become resistance

Answer 54

1. do not interact with drug (barrier, destroy drug, etc.)
2. change the target (alter so drug cannot effect target)

Question 55

Watch lecture 20 through slide 32

Question 56

Drug resistance can be aquired via…

Answer 56

horizontal gene transfer

Question 57

How to fight drug resistance

Answer 57

1. only use drugs when they are useful
2. multidrug therapy
3. dummy targets to inactivaate resistance enzymes
4. alter antibiotic structure

Question 58

if it ends in -cillin then it is a

Answer 58

beta lactam

Question 59

Clarulanic acid binds to ____ so that S. aureus does not cleave ____.

Answer 59

Beta lactamase, amoxicillin