Antimicrobrial chemotherapy- mechanisms of action

Question 1

What are antibiotics active against?

Answer 1

bacteria

Question 2

What is a bactericidal?

Answer 2

antimicrobial that kills bacteria

Question 3

What is M.B.C?

Answer 3

minimal bactericidal concentration - minimum conc of antimicrobial needed to kill a given organism

Question 4

What is bacteriostatic?

Answer 4

they do not kill bacteria but they inhibit the growth

Question 5

What is MIC?

Answer 5

minimal inhibitory concentration- minimum concentration of antibiotic you need in order to inhibit the growth of the specific organism

Question 6

What are the different routes of antibiotic administration?

Answer 6

topical: applied to surface
systemic: taken internally
parenterally: administered intravenously or intramuscularly

Question 7

What are the classifications of sypherical, cocci bacteria?

Answer 7

diplococci, streptococci, staphylococci

Question 8

What are the classifications of rod, bacilli bacteria?

Answer 8

chain of bacilli, flagellate rods, spore former

Question 9

What are the classifications of spirals bacteria?

Answer 9

vibrios, spirilla, spirochettes

Question 10

What are gram negative cocci?

Answer 10

neisseria
morasella

Question 11

What are gram positive cocci?

Answer 11

staphylococcus
streptococcus
enterococcus
pneumococcus

Question 12

What are gram negative bacilli?

Answer 12

escherichia coli
shigella
salmonella

Question 13

What are gram positive bacilli?

Answer 13

corynebacterium
clostridium
listeria monocytogenes

Question 14

What are the gram negative spirals?

Answer 14

vibrio cholerae
helicobacter pylori

Question 15

How do the antibiotics work when they want to kill or inhibit the growth of specific bacteria?

Answer 15

Antibiotics may inhibit or kill bacteria by acting at three different areas of metabolic activity.

-inhibition of cell wall synthesis
-inhibit protein synthesis
-inhibition of nucleic acid synthesis

Question 16

Why do antibiotics not interfere with human cells?

Answer 16

Human cells do not have any kind of cell wall

Question 17

What antibiotics inhibit the cell wall synthesis?

Answer 17

Beta-lactams- Penicillins and Cephalosporins

Question 18

Give characteristics of beta lactam antibiotics?

Answer 18

-bactericidal antibiotics
-effective mostly against Gram-positive bacteria

Question 19

Why are penicillin and cephalosporins classified as beta lactams?

Answer 19

chemical structure of drugs contain a beta lactam ring (square)

Question 20

Why are many gram negative organisms resistant to benzyl penicillin?

Answer 20

inability to penetrate gram negative cell wall

Question 21

Describe how glycopeptides (bactericidal antibiotics) are able to inhibit the cell wall synthesis?

Answer 21

-prevent two peptidoglycans to join
together to create a more stable cell wall
-vancomycin (glycopeptide) is going to prevent the two peptidoglycans to link to each other
-cell wall is disrupted

Question 22

Describe how penicillins and cephalosporins inhibit cell wall synthesis?

Answer 22

interfere with the specific kind of enzyme involved in the cross link between peptidoglycan bridges and cell wall. On the enzyme itself there is a specific binding site for the penicillin drug. Penicillin will interact with enzyme and inhibit it. Cell wall less strong

Question 23

How would you administer glycopeptides?

Answer 23

-can’t be given orally as cannot be absorbed by gastrointestinal tract, only given parentally

Question 24

What are the kind of antibiotics that are able to inhibit the protein synthesis of bacteria?

Answer 24

aminoglycosides

Question 25

Give characteristics of aminoglycosides?

Answer 25

inhibit the protein synthesis concentration-dependent bactericidal antibiotics useful in the treatment of serious Gram-negative infection

Question 26

How do aminoglycosides work?

Answer 26

antibiotic going to interfere with protein synthesis and prevent proper protein to be created.

Answer 27

There are some differences between the ribosome structure in the bacteria and the mammalian ribosome. This makes antibody specific for bacteria, as antibody can discriminate between ribosomes. Targets 70S ribosome

Question 28

Give example of aminoglycoside?

Answer 28

gentamicin

Question 29

Give characteristics of macrolides?

Answer 29

useful alternatives to penicillins in treatment of Gram positive infections in patients who are penicillin allergic.

Question 30

Give name of a macrolide that can be used instead of penicillin?

Answer 30

erythromycin

Question 31

Give characteristics of tetracyclines?

Answer 31

bacteriostatic antibiotics treatment of gram positive infections

Question 32

What bacteria is resistant to tetracycline?

Answer 32

percentage of bacteria like staphylococcus aureus, streptococcus pyogenes and streptococcus pneumonia that are actually resistant to the tetracycline.

Question 33

Give characteristics of oxazolidinones?

Answer 33

bacteriostatic or bactericidal treatment of gram positive infections last resort

Question 34

Give an example of an oxazolidinones?

Answer 34

linezolid

Question 35

Give characteristics of cyclic lipopeptides?

Answer 35

strong bactericidal antibiotics treatment of gram positive

Question 36

Give example of a cyclic lipopeptide?

Answer 36

daptomycin

Question 37

How does the specific antibiotic, trimethoprim work?

Answer 37

inhibition of purine synthesis bacteriostatic alone but when combined with antibiotics- bactericidal inhibition of DNA synthesis either directly, or indirectly by interrupting the supply of precursors for DNA synthesis

Question 38

When is trimethoprim used?

Answer 38

treatment of urinary tract and chest infections

Question 39

Give another example of inhibitor of purine synthesis?

Answer 39

sulphamethoxazole

Question 40

What is co-trimoxazole a combination of?

Answer 40

trimethoprim and sulphamethoxazole

Question 41

Give characteristics of fluoroquinolones?

Answer 41

bactericidal antibiotics particularly effective against gram negative inhibiting enzyme involved in DNA synthesis used orally as well as parenterally

Question 42

Give examples of fluroquinolones?

Answer 42

ciprofloxacin levofloxacin- can be used against gram pos