Introduction to antibiotics

Question 1

what is the main principle of antimicrobial chemotherapy?

Answer 1

drugs should be toxic to invading microorganisms but not to the host.

Question 2

what is the key feature of bacterial cells?

Answer 2

no nucleus

peptidoglycan cell wall

Question 3

what is the limitation of class 1 bacterial metabolism as a drug target?

Answer 3

its similar to host reactions, multiple pathways to produce energy
produce ATP and simple carbon compounds

Question 4

what is advantage of class 2 bacterial metabolism as a drug target?

Answer 4

the folate biosynthetic pathway.

use energy and class one compounds to make small compounds

humans can make folate from diet, bacteria lack folate transporters

Question 5

what is the main advantage of class 3 bacterial metabolism as a drug target?

Answer 5

good target as it better differentiates between pathogen and host cells

Question 6

what is class 2 reactions

Answer 6

use ATP and class 1 compounds to make small molecules

Question 7

what are sulphonamides?

Answer 7

are a class of antibiotics that inhibit bacteria from producing its own folate.
this can commonly cause allergic reactions so is avoided

Question 8

what is trimethoprim?

Answer 8

a class of antibiotics that inhibits dihdryofolate reductase in bacteria .
it doesn't affect human production of tetrahydrofolate.
this can be used to treat urine infections

Question 9

what is an advantage of trimethoprim?

Answer 9

it can be used to treat gram positive and negative bacteria.
its a broad spectrum antibiotic.

Question 10

what is a class 3 reaction?

Answer 10

converts starch into macromolecules

Question 11

what is an advantage of class 3 reactions as a target site?

Answer 11

better at differentiating between pathogen and host cell

Question 12

what is penicillin and cephalosporins better at treating?

Answer 12

both used for gram positive infections

Question 13

what infection type is harder to treat with antibiotics?

Answer 13

gram negative

Question 14

what are the bacterial ribosomes?

Answer 14

50s and 30s

Question 15

what are the human ribosomes?

Answer 15

60s and 40s

Question 16

how do tetracyclines work?

Answer 16

by preventing tRNA binding to the ribosome

Question 17

how does chloramphenicol work?

Answer 17

it inhibits transpeptidation - causing premature termination of peptide chain

Question 18

how does aminoglycosides work?

Answer 18

disrupt codon ; anticodon - misreading of message

Question 19

how do macrolides work?

Answer 19

disrupt translocation (moving on of used tRNA)

Question 20

name three examples of broad spectrum antibiotics

Answer 20

trimethoprim, macrolides and tetracylclines

Question 21

what do anti-viral drugs target?

Answer 21

different stages of the viral replication stage

Question 22

what are the 7 steps of the viral replication stage?

Answer 22

1. attachment
2. penetration
3. uncoating
4. replication of nucleic acid
5. synthesis of protein coats
6. assembly
7. release

Question 23

what stage of viral replication does tamiflu work on (for influenza)

Answer 23

7. release

tamiflu is a neuraminidase inhibitor

Question 24

what stage of viral replication is acyclovirs target (drug for herpes virus)

Answer 24

4. replication of nucleic acid

Question 25

what stage of viral replication is the target for HIV treatment?

Answer 25

multiple stages

1. attachement
2. penetration
3. replication of nucleic acid
4. protease inhibitors

Question 26

what are some of the mechanisms of bacterial antibiotic resistance?

Answer 26

• production of enzymes that inactivate drug e.g. beta lactamases
• alteration of drug binding site e.g. penicillin
• reduction of drug update by bacterium e.g. tetracylclines
• alteration of enzyme pathways e.g. trimethoprim

Question 27

what class stage is of bacterial reactions if peptidoglycan produced in?

Answer 27

class 3 reactions

Question 28

what is the mechanism of action of penicillin?

Answer 28

penicillin forms covalent bonds with proteins with transpeptidase and carboxypeptidase activity.

inhibits binding of cross linking peptides to peptidoglycan side chains

Question 29

what class of antiviral drugs is used to treat herpes virus infection?

Answer 29

guanosine analogues ie. acyclovir prevents nucleic acid synthesis and are used in the treatment of herpes virus infections

Question 30

what would be the main and most important reason drugs shouldn’t be used to treat viral sore throats?

Answer 30

it increases antibiotic resistance - therefore decreasing the effectiveness of antibiotics