Ch 12 Chemotherapy

Question 0

Antibiotic

Answer 0

An antimicrobial that is produced by the natural metabolic processes of some microorganisms, that can inhibit or destroy others. “Biological warfare “

Question 1

Define antimicrobial

Answer 1

All inclusive term for any antimicrobial drug regardless of origin

Question 2

Selectively toxic

Answer 2

Kill or inhibit microbes but not harm host

Question 3

Broad spectrum

Answer 3

Effective against a wide variety of microbial types. ex: gram-positive and gram-negative

Question 4

Narrow spectrum

Answer 4

Effective against a limited array of microbial types. Ex: only gram-positive

Question 5

Examples of antibiotics that affect bacteria Cell walls

Answer 5

“Cillins” and cephalosporins, Augmentin, vancomycin bacitracin, Neosporin

Question 6

Explain the mechanism of action of cephalosporins and “cillins”

Answer 6

cephalosporins and “cillins”have a beta lactam ring that lures transpeptidase away from bacteria preventing transpeptidase and so it cannot divide

Question 7

What do some bacteria have that specifically causes resistance to antibiotics

Answer 7

Beta lactamase

Question 8

What can be added to “cillins” that stops the bacteria’s resistance to antibiotics

Answer 8

Clavulanic acid

Question 9

How does Clavulanic acid work

Answer 9

Mimic’s the beta-lactam ring causing beta-lactamase to bind to it allowing transpeptidation to continue

Question 10

Most antibiotics are the product of which two genera of molds

Answer 10

Penicillium and Cephalosporium

Question 11

Antibiotics are the product of which 2 genera of bacteria

Answer 11

Bacillus and streptomyces

Question 12

Explain the mechanism of drug action when it affects nucleic acid synthesis

Answer 12

Inhibits replication or transcription

Question 13

Two examples of antibiotics that affect nucleic acid synthesis

Answer 13

Ciprofloxacin and rifamycin

Question 14

Explain how aminoglycosides (Streptomycin) affect protein synthesis

Answer 14

Bonds to the smaller subunits of a ribosome so that mRNA is translated incorrectly; ** protein is still built but will be incorrect**

Question 15

Antibiotics typically affect what size ribosomes

Answer 15

70S

Question 16

Explain how chloramphenicol affects protein synthesis

Answer 16

Stops the peptide bond from forming between the amino acids. Protein is NOT assembled

Question 17

Explain how oxazolidinones affect protein synthesis

Answer 17

Blocks initiation (prevents large subunit from attaching two small subunit). Protein is not assembled

Question 18

Explain how tetracyclines affect protein synthesis

Answer 18

Blocks tRNA from entering the ribosome. Protein is not assembled

Question 19

Explain how erythromycin affects protein synthesis

Answer 19

Blocks the exit, stops translation. “Translocation of mRNA blocked” protein is not assembled

Question 20

Of all the examples of drugs that affect protein synthesis only one still builds a protein. Which one is it

Answer 20

Aminoglycosides (streptomycin)

Question 21

Explain the drugs that affect cell membrane function

Answer 21

Not normally first choice, disrupt bacteria membranes by interacting with the phospholipids causing leakage of proteins (similar to how surfactants or detergents work)
Polymyxins

Question 22

What are examples of drugs that affect folic acid synthesis in bacteria and why are they effective

Answer 22

Sulfonamides (sulfa drugs) because bacteria cannot make their own folic acid

Question 23

How do antibiotics that affect folic acid synthesis work

Answer 23

Act as competitive inhibitors by occupying the active site so the normal substrates can’t enter; sulfonamides (sulfa drugs)

Question 24

Examples of what antifungals treat and what they target

Answer 24

Target fungi ; ex: yeast infection, jock itch, athletes foot

Question 25

What do antiparasitic’s target

Answer 25

Target parasites (protozoans) 
ex: chlamydia, amoeba

Question 26

Antivirals

Answer 26

Target viruses. Ex: Tamiflu and Valtrex

Question 27

Two ways in which microbes can acquire drug resistance

Answer 27

Spontaneous mutations in chromosome or acquisition of new genes via horizontal gene transfer

Question 28

Name the six mechanisms of drug resistance

Answer 28

Drug inactivating mechanisms, decreased drug permeability or increased drug elimination, change of drug receptors, change in metabolic patterns, natural selection, change the site that the drug affects

Question 29

Probiotics or prebiotic’s are referred to as

Answer 29

“Good germs “

Question 30

Three possible undesirable drug interactions

Answer 30

Toxicity to organs, allergic reactions, suppression of normal flora

Question 31

What does the Kirby Bauer method test for

Answer 31

A microbes Sensitivity to different antibiotics

Question 32

Three possible results of the Kirby Bauer test

Answer 32

Resistance, intermediate, sensitive

Question 33

What is the zone of inhibition

Answer 33

The zone around the disk of antibiotics where no growth occurs

Question 34

What is meant by the minimal inhibitory concentration of an anabiotic

Answer 34

Lowest dosage of a drug that will prevent growth; Growth remains constant

Question 35

What is meant by the minimal lethal concentration of a drug

Answer 35

The lowest dosage of a drug that will kill bacteria, no living cells are present

Question 36

How is the therapeutic index of a drug calculated

Answer 36

It is a ratio of the dosage that is toxic to humans divided by the minimal inhibitory concentration

Question 37

Explain how to pick a drug based on the therapeutic index

Answer 37

The higher the ratio the safer the drug