Antibiotics

Question 1

What are the bacteria that are commonly used to determine the activity spectrum of an antibiotic?

Answer 1

Gram (+), Gram (-), mycobacteria, pseudomonas

Question 2

Difference between bacteriostatic, bactericidal, and a bacteriolytic antibiotic.

Answer 2

‘static = prevents growth
‘cidal = kills bacteria
‘lytic = causes lysis

Question 3

What is a therapeutic index

Answer 3

range of doses that are effective without causing unacceptable adverse events (or harm)

Question 4

What are four common unwanted side effects of antibiotic use

Answer 4

1. Allergies develop
2. Toxicity (end up affecting human cells)
3. Suppression of normal flora
4. Selection for antibiotic resistant “superbugs”

Question 5

Why are several successive generations of antibiotics produced?

Answer 5

To improve the antibiotic by changing its properties or administration route

Question 6

What are five major antibiotic targets in bacteria

Answer 6

1. Lipid membrane
2. Cell wall (peptidoglycan)
3. Nucleic acid synthesis
4. Protein synthesis
5. Folate biosynthesis

Question 7

Mode of action: beta-lactams

Answer 7

cell wall
prevent PG crosslink
can be inactivated by beta-lactamase enzymes (resistance)

Question 8

Mode of action: vancomycin

Answer 8

cell wall
prevent PG transglycosylation and transpeptidation

Question 9

Mode of action: bacitracin

Answer 9

cell wall
prevent monomer transport across membrane

Question 10

Mode of action: fluoroquinolones

Answer 10

Nucleic acid synthesis
inhibit gyrase

Question 11

Mode of action: rifamycin

Answer 11

Nucleic acid synthesis
inhibit RNA polymerase

Question 12

Mode of action: polymyxin

Answer 12

cell membrane
peptide antibiotic

Question 13

Mode of action: cubucin

Answer 13

cell membrane
dissipates PMF

Question 14

Mode of action: sulfa drugs

Answer 14

folic acid synthesis
competitive inhibitor for PABA

Question 15

Mode of action: trimethoprim

Answer 15

inhibits intermediate in folic acid synthesis

Question 16

What five antibiotic are protein synthesis inhibitors

Answer 16

Synercid
Macrolide
Aminoglycoside
Lincosamide
Linezolid

Question 17

What are four major targets of antiviral drugs

Answer 17

Uncoating (nucleic acid liberation)
Synthesis
Assembly
Release

Question 18

Mode of action of amantadine and oseltamivir on influenza virus

Answer 18

amantadine: targets uncoating in flu virus
oseltamivir: inhibits neuraminidase (release) in flu

Question 19

What are the three main classes of nucleic acid synthesis inhibitors

Answer 19

1. nucleoside analogs
2. polymerase inbibitors
3. RTase inhibitors

Question 20

How do protease inhibitor drugs prevent the assembly of some viruses

Answer 20

inhibits protease

Question 21

What are the main targets of antifungal drugs + examples

Answer 21

1. Plasma membrane (azoles)
2. Cell wall (echinocandins)
3. Cell division (griseofulvin)

Question 22

What are five antiprotozoal drugs + uses

Answer 22

Intestinal infections
a. Metronidazole
Helminths
b. Ivermectin
c. Piperazine
Malaria
d. Artemisinin
e. Chloroquine

Question 23

What are three ways to determine the effectiveness of an antibiotic against a particular bacterium

Answer 23

1. Minimum Inhibitory Concentration (serial dilution)
2. Kirby Baur Susceptibility testing (disc)
3. E test (strip)

Question 24

What are four mechanisms where bacteria develop resistance

Answer 24

1. Destroy antibiotic
2. Chemically modify antibiotic
3. Alter target of antibiotic
4. Decrease uptake

Question 25

What are R-plasmids?

Answer 25

R plasmids are a type of F plasmid that have multiple genes for resistance, it can be transmitted by transformation, conjugation, or transduction

Question 26

How can bacteria can become resistant to several antibiotics if they were only exposed to one?

Answer 26

multiple drugs may target the same mechanism