Ch.20 Antimicrobial Drugs

Question 1

narrow spectrum antibiotics

Answer 1

is effective against specific families of bacteria.

Question 2

broad-spectrum antibiotics

Answer 2

refers to antibiotics that act against a wide range of disease-causing bacteria.

Question 3

superinfection:

Answer 3

overgrowth of normal microbiota that is resistant to antibiotic

Question 4

bactericidal:

Answer 4

kill microbes directly

Question 5

Major Action Modes of Antibacterial Drugs

1. inhibition of cell wall synthesis:

Answer 5

penicillins

cephalosporins

bacitracin

vancomycin

Question 6

bacteriostatic:

Answer 6

prevent microbes from growing

Question 7

Major Action Modes of Antibacterial Drugs

2. inhibition of protein synthesis

Answer 7

chloramphenicol

erythromycin

tetracyclines

streptomycin

Question 8

Major Action Modes of Antibacterial Drugs

3. inhibition of nucleic acid replication and transcription

Answer 8

quinolones

rifampin

Question 9

Major Action Modes of Antibacterial Drugs

4. injury to the plasma membrane:

Answer 9

polymyxin B

Question 10

Major Action Modes of Antibacterial Drugs

5. inhibition of essential metabolite synthesis:

Answer 10

sulfanilamide

trimethoprim

Question 11

The action of microbial drugs:

inhibiting cell wall synthesis of peptidoglycan

Answer 11

Penicillins prevent the synthesis
of peptidoglycan

Question 12

The action of microbial drugs:

injuring the plasma membrane

Answer 12

Polypeptide antibiotics change
membrane permeability.

Ionophore antibiotics: allow for uncontrolled movement of cations

Question 13

The action of microbial drugs:

Inhibiting protein synthesis

Answer 13

Target bacterial 70S ribosomes

‒ Chloramphenicol, erythromycin,
streptomycin, tetracycline

Question 14

Streptomycin

Answer 14

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

Question 15

tetracyclines

Answer 15

interfere with the attachment of tRNA to mRNA-ribosome complex

Question 16

The Action of Antimicrobial Drugs

inhibiting nucleic acid synthesis

Answer 16

interfere with DNA replication and transcription

Rifamycin, quinolones (nalidixic acid) & fluoroquinolones

Question 17

The Action of Antimicrobial Drugs

inhibiting the synthesis of essential metabolites

Answer 17

anti-metabolites compete with the normal substrate for the enzyme

Question 18

Modes of Antiviral Drugs

Answer 18

1. Entry and fusion inhibitors
2. Uncoating, genome integration, and nucleic acid synthesis inhibitors
3. Assembly and exit inhibitors
4. Interferons

Question 19

Entry & fusion inhibitor

Answer 19

Block the receptors on the host cell that bind to the virus

‒ Block fusion of the virus and cell

Question 20

Uncoating, genome integration, and nucleic acid synthesis
inhibitors

Answer 20

Prevent viral uncoating

‒ Inhibit viral DNA integration
into the host genome

‒ Nucleoside analogs inhibit RNA/ DNA synthesis

Question 21

assembly and exit inhibitors

Answer 21

‒ Protease inhibitors: block the cleavage of inhibitor cleavage of protein precursors

‒ Exit inhibitors: inhibit neuraminidase, an enzyme required for some viruses to bud from the host cell

Question 22

interferons

Answer 22

Produced by viral-infected cells to inhibit further spread of the
infection

Question 23

Imiquimod:

Answer 23

promotes interferon production

Question 24

antiretroviral drug is used to treat

Answer 24

HIV infections

Question 25

persister cells:

Answer 25

microbes with genetic characteristics allowing for their survival when exposed to an antibiotic

Question 26

superbugs:

Answer 26

bacteria that are resistant to a large number of antibiotics

Question 27

Mechanisms of Resistance

Answer 27

Enzymatic destruction or inactivation of the drug

• Prevention of penetration to the target site within the microbe
• Alteration of the
  drug’s target site
• Rapid efflux (ejection)
  of the antibiotic
• Variations of
  mechanisms of
  resistance

Question 28

Resistance genes are often spread

Answer 28

horizontally among bacteria
on plasmids or transposons via conjugation or transduction

Question 29

Antibiotic Misuse

Answer 29

Using outdated or weakened antibiotics

Using antibiotics for the common cold and other
inappropriate conditions

Using antibiotics in animal feed

Failing to complete the prescribed regimen

Using someone else’s leftover prescription

Question 30

synergism

Answer 30

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

Question 31

antagonism

Answer 31

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