Antibiotics

Question 1

Antibiotics

Answer 1

chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species

Question 2

Another name for antibiotics:

Answer 2

“magic bullet”

Question 3

An antimicrobial drug has _________ __________ if it kills microbial cells, but does not kill host cells.

Answer 3

selective toxicity

Question 4

–cidal

Answer 4

kills microbes directly

Question 5

–static

Answer 5

prevents microbes from growing

Question 6

broad spectrum

Answer 6

effective against wide range of species, including both gram negative and gram positive species

Question 7

example of a broad spectrum antibiotic

Answer 7

tetracycline

Question 8

narrow spectrum

Answer 8

only active against select species

Question 9

example of a narrow spectrum antibiotic

Answer 9

penicillin G

Question 10

What are gram negative more resistant?

Answer 10

outer membrane of gram negative species inhibits the passage of many antiobiotics

Question 11

Superinfection

Answer 11

Ab tx, especially broad-spectrum, may destroy normal flora

Question 12

What happens in times of superinfection?

Answer 12

Ab resistant microbes (Candida albicans) can grow unchecked

Question 13

4 Mechanisms of Action Ab’s use

Answer 13

1. Inhibition of cell wall synthesis
2. Inhibition of protein synthesis
3. Inhibition of nucleic acid replication and transcription
4. Inhibition of essential metabolite synthesis

Question 14

Natural penicillin

Answer 14

Narrow spectrum of range; susceptible to penicillinase

Question 15

What type of bacteria is penicillin effective against and why?

Answer 15

gram (+) - interferes with cross-linking of peptidoglycan

Question 16

Semi-synthetic penicillin

Answer 16

extended spectrum and/or resistance to penicillinase

Question 17

Penicillinase

Answer 17

a beta-lactamase enzyme effective against penicillin

Question 18

How does penicillinase work?

Answer 18

cleaves beta-lactam ring

Question 19

4 features of Colistin

Answer 19

1. disrupts outer membrane of gram negative cell wall
2. disrupts plasma membrane
3. cell lysis
4. last resort due to nephrotoxicity

Question 20

2 Mycobacterium species

Answer 20

leprosy and TB

Question 21

Isoniazid

Answer 21

inhibits mycolic acid synthesis

Question 22

ethambutol

Answer 22

inhibits corporation of mycolic acid

Question 23

3 things that inhibit replication?

Answer 23

ciproflaxin, nalidixic acid, UTIs

Question 24

What does Rifamycin do?

Answer 24

inhibit transcription by selectively binding to the bacterial RNA polymerase

Question 25

chloramphenicol

Answer 25

binds to 50S portion and inhibits formation of peptide bond

Question 26

streptomycin

Answer 26

changes shape of 30S portion causing code on mRNA to be read incorrectly

Question 27

tetracycline

Answer 27

interfere with attachment of tRNA to mRNA-ribosome complex?

Question 28

Chloramphenicol, Streptomycin, and Tetracycline inhibit what?

Answer 28

Protein synthesis

Question 29

An inhibitor of metabolic enzymes

Answer 29

sulfonamides

Question 30

Sulfonamides are ________ inhibitors. They inhibit ____ ____ _____. They are a ________ _________ antibiotic.

Answer 30

competitive; folic acid synthesis; broad spectrum

Question 31

Erythromycin inhibits translation. Why does erythromycin have a spectrum of activity limited largely to gram positive bacteria?

Answer 31

The gram-negative cell wall blocks erythromycin.

Question 32

Primary sterol in fungal membranes

Answer 32

ergosterol

Question 33

primary sterol in animal membranes

Answer 33

cholesterol

Question 34

Examples of antifungals that target ergosterol synthesis:

Answer 34

Azoles like miconazole and triazole

Question 35

Flucytosine

Answer 35

cytosine analog interferes with RNA synthesis

Question 36

Griseofulvin

Answer 36

inhibits microtubule formation

Question 37

MIC

Answer 37

minimal inhibitory concentration

Question 38

MBC

Answer 38

minimal bactericidal concentration

Question 39

2 ways to measure susceptibility of drug:

Answer 39

Disk Diffusion Method (Kirby-Bauer Test) & Broth dilution

Question 40

Synergism

Answer 40

occurs when the effect of two drugs together is greater than the effect of either alone

Question 41

Antagonism

Answer 41

occurs when the effect of two drugs together is less than the effect of either alone

Question 42

4 Mechanisms of Ab Resistance

Answer 42

1. blocking entry
2. inactivation by enzymes
3. alteration of target molecules
4. efflux of antibiotic

Question 43

MDR Pump

Answer 43

Multi-drug resistance; can export many kinds of Abs

Question 44

Amphotericin B

Answer 44

binds to ergosterol and forms pores in membrane; cytotoxic, generally used only for severe systemic infections

Question 45

2 ways in which bacteria acquire Ab resistane?

Answer 45

1. Mutation during DNA replication

2. Horizontal transfer

Question 46

Horizontal Transfer

Answer 46

resistance genes are often on plasmids or transposons that can be transferred between bacteria

Question 47

Problems with Antivirals

Answer 47

Difficult to find because there are few targets you can use (selective toxicity issues)

Question 48

Amantadine

Answer 48

inhibits viral uncoating (preventing entry of virus into host cell)

Question 49

Zanamavir

Answer 49

blocks neurominidase (the spikes on the outside of viruses; this prevents them from being released)

Question 50

Acyclovir

Answer 50

analog of guanosine that has no 3’ OH. The chain terminates thus blocking DNA synthesis (including yours)

Question 51

Ribavirin

Answer 51

Lowers fidelity of RNA polymerase,

Question 52

AZT (azidothymidine)

Answer 52

nucleoside analog reverse transcriptase inhibitor

Question 53

interferons

Answer 53

normal host proteins that prevent spread of viruses to new cells

Question 54

alpha interferon

Answer 54

used to tread viral hepatitis

Question 55

imiquimod

Answer 55

promotes interferon production