Effects of Antibiotics on Life Cycle of bacteria

Question 1

what is the difference b/w bactericidal and bacteriostatic

Answer 1

bactericdal kills all whereas bacteriostatic slows activity

Question 2

what are the characteristics of an ideal antibiotic ?

Answer 2

broad spectrum of activity, no resistance, high therapeutic index, selective toxicity

Question 3

what does a low therapeutic index mean for an antibiotic

Answer 3

it means it will take a toxic dose (to the host) in order to kill the bacteria

Question 4

what 4 parts of bacteria should you attack to achieve selective toxicity

Answer 4

cell wall, unique replication/transcription enzymes, unique metabolites, ribosomes

Question 5

what are the 5 main ways to inhibit bacteria

Answer 5

1-inhibit cell wall synthesis
2-disrupt cell membrane function
3-inhibit protein synthesis
4-inhibit nucleic acid synthesis
5-act as antimetabolite

Question 6

how does penicillan act to inhibit bacteria

Answer 6

disrupts cell wall synthesis

Question 7

what does polymyxin B sulfate do to inhibit bacteria, and what is its drawback as an antibiotic

Answer 7

disrupts cell membrane function, but also attacks eukaryotes so only used as a topical antibiotic

Question 8

what is the most common strategy for an antibiotic to inhibit bacteria, Why ?

Answer 8

inhibit protein synthesis, because the bacterial ribosome is structurally different than the eukaryotic ribisome

Question 9

what enzymes would an antibiotic attack if it were inhibiting nucleic acid synthesis

Answer 9

DNA gyrase (bacteria only have this), RNA polymerase

Question 10

T/F an antibiotic trying to inhibit nucleic acid synthesis is good if it binds to DNA ?

Answer 10

F, do NOT want it to bind to DNA else would be toxic to host human

Question 11

what specific antibiotic acts as an antimetabolite

Answer 11

sulfanilamide

Question 12

macrolides, linezoid,tetracycline, and aminoglycosides all have what in common ?

Answer 12

antibiotics that block the ribosome cycle thus blocking protein synthesis

Question 13

what is the main cause of bacteria to develop antibiotic resistance

Answer 13

selective pressure and overuse

Question 14

what are the 3 steps in the action of an antibiotic to be effective

Answer 14

1 - penetrate the envelope
2-transport into the cell
3-bind to target

Question 15

what are the 3 mechanisms of drug resistance

Answer 15

1-synthesis of enzymes that inactivate drug
2- prevention of access to target site
3-modificaton of target site

Question 16

Beta lactamases is an example of what kind of enzyme

Answer 16

an enzyme bacteria have developed that inactivates penicillan (caused bacteria resistance)

Question 17

bacteria developing efflux pumps to pump tetracycline out of the cell is a demonstration of what mechanism of drug resistance

Answer 17

preventing access to the target site

Question 18

if bacteria can modify an enzymes affinity for a particular drug it is an exp of what mechanism of drug resistance

Answer 18

modification of the target site

Question 19

what are the 3 ways antibiotic resistance can spread

Answer 19

1-chromosome associated resistance
2-plasmid mediated resistance
3-rapid spread of resistance

Question 20

why it is so crucial to completely finish an antibiotic for the reccomended time period

Answer 20

Because an antibiotic will kill the most sensitive bacteria 1st, then the int. bacteria, and lastly the highly resistant bacteria (if dont finish wont kill this last group then your fucked )

Question 21

3 ways to combat an antibiotic resistant pathogen

Answer 21

synergism, antagonism, indifference

Question 22

what is the difference b/w synergism and antoagonism antibiotics

Answer 22

synergism uses 2 drugs to amplify effect, antagonism uses 2 but 1 is bacteriostatic and other is bactericidal

Question 23

T/F antibiotics are effective against all microbes

Answer 23

F, do not affect virus

Question 24

what are potential drawbacks of administering an antibiotic cocktail (2 or more drugs together)

Answer 24

• could become resistant to 2 drugs
• doesnt eliminate bacteria and get superinfection
• synergistic toxicity to host