Ch. 13

Question 1

What is the goal of antimicrobial chemotherapy?

Answer 1

To administer a drug to an infected person that destroys the infective agent without harming the host’s cells

Question 2

Common metabolic products of bacteria and fungi.

Answer 2

Antibiotics

Question 3

How are semisynthetic drugs created?

Answer 3

By chemically altering the structure of naturally occurring antibiotics

Question 4

Why are synthetic drugs used?

Answer 4

Because you can’t get some natural compounds without destroying a habitat or population so drugs created in a lab mimic the action of natural compounds

Question 5

Central concept in antibiotic treatment; antimicrobial drugs should kill or inhibit microbial cells without simultaneously damaging host tissues.

Answer 5

Selective toxicity

Question 6

The best drugs block actions of molecules in microorganisms but not ___ cells.

Answer 6

Vertebrate cells

Question 7

Name a drug with excellent selective toxicity

Answer 7

Penicillins because they block the synthesis of the cell wall found only in bacteria

Question 8

What characteristics make a drug most toxic to human cells?

Answer 8

Drugs that act upon a structure common to both the infective agent and the host cell

Question 9

When does selective toxicity become more difficult?

Answer 9

As the characteristics of the infectious agent become more similar to that of the host

Question 10

What are the metabolic targets of chemotherapeutic agents?

Answer 10

Inhibition of: cell wall synthesis, nucleic acid (DNA/RNA) structure/function, protein synthesis, folic acid synthesis

Interference with: cell membrane structure/function

Question 11

Drugs that are affective against more than one group of bacteria. Give an example.

Answer 11

Broad spectrum drugs. Example: tetracyclines

Question 12

Drugs that only target a specific group. Give an example.

Answer 12

Narrow spectrum drugs. Example: polymyxin and penicillins

Question 13

Drugs that target protein synthesis. Broad spectrum. What are the side effects?

Answer 13

Tetracyclines. Side effects include gastrointestinal disruption and deposition in hard tissues

Question 14

Drugs that target folic acid synthesis. First modern antimicrobial drugs. Synthetic.

Answer 14

Sulfonamides or sulfa drugs

Question 15

What do Biofilms do?

Answer 15

Interrupt quorum sensing pathways and add DNAse to antibiotics; pretreatment

Question 16

What is quinine?

Answer 16

An antimalarial drug that was the principal treatment for hundreds of years. Replaced by less toxic chloroquine and primaquine

Question 17

What are protozoan infections?

Answer 17

Parasitic diseases

Question 18

An antibiotic used as chemotherapy for other protozoan infections

Answer 18

Metronidazole (an amoebicide)

Question 19

What are the three major modes of action for antiviral chemotherapeutic agents?

Answer 19

1) Barring penetration of virus into host cell
2) Blocking transcription and translation of viral molecules
3) Preventing maturation of viral particles

Question 20

Adaptive response in which microorganisms begin to tolerate an amount of drug that would ordinarily be inhibitory

Answer 20

Drug resistance

Question 21

Bacteria must be resistant to any antibiotic that they themselves produce

Answer 21

Intrinsic resistance

Question 22

Bacterial resistance to a drug which they were previously sensitive

Answer 22

Acquired resistance

Question 23

What are three ways drug resistance can develop?

Answer 23

1) resistance through spontaneous mutation
2) resistance through horizontal transfer
3) sharing of resistance genes accounts for the rapid proliferation of drug-resistant species

Question 24

Plasmids that are transferred through conjugation, transformation, or transduction

Answer 24

Resistance (R) factors (resistance through horizontal transfer

Question 25

The ratio of the dose of the drug that is toxic to humans to its minimum effective dose (closer two figures are to each other greater potential for toxic drug reactions)

Answer 25

Therapeutic index (TI)

Question 26

Smallest concentration of drug that visibly inhibits growth. Helps determine smallest effective dose.

Answer 26

Minimum inhibitory concentration (MIC)

Question 27

If treatment fails, what are some possible reasons why?

Answer 27

Inability of drug to diffuse into body compartment; resistant microbes in infection that don’t make it into sample collected for testing; infection caused by more than one pathogen mixed, some of which are resistant to the drug

Question 28

Explain the livestock bacteria situation

Answer 28

Enteric (intestinal) bacteria share resistance plasmids that are constantly selected and amplified by exposure to drugs. These pathogens jump to humans and cause drug-resistant infections

Question 29

What is the novel approach to antimicrobial therapy?

Answer 29

Disabling host molecules that the invaders use to enhance their position

Question 30

Why is phage a low tech solution?

Answer 30

Extremely specific and only infect one species of bacteria, leaving normal microbiota alone

Question 31

Preparations of live microorganisms fed to animals and humans to improve intestinal biota. Replace microbes lost during antimicrobial therapy. Help the biota already there.

Answer 31

Probiotics (ex: probiotic yogurt)

Question 32

Nutrients that encourage growth of beneficial microbes in the intestine

Answer 32

Prebiotics.

Question 33

Example of a prebiotic; encourage growth of bifidobacterium in the large intestine and discourage the growth of pathogens; a polymer of fructose molecules and occur in agave, artichokes,wheat, onions, etc.

Answer 33

Fructans

Question 34

Bind to the enamel of teeth and turn gray/brown. Cause liver damage in pregnant women. Cross the placenta and are deposited in fetal bones and teeth

Answer 34

Tetracyclines