antimicrobial drugs (antibiotics)

Question 1

define bactericidal and bacteriostatic antibiotics?

Answer 1

bactericidal - kill bacteria. bacteriostatic -inhibit and arrest the growth of bacteria.

Question 2

describe what is meant by; broad spectrum antibiotics, narrow spectrum antibiotics and limited spectrum antibiotics?

Answer 2

broad - targets a range of bacterial species.
narrowed - targets a limited number of bacteria.
limited - targets a single bacteria species

Question 3

general action of antibiotics?

Answer 3

interfere with and inhibit cellular structures and processes of bacteria, target bacteria-specific structures, are toxic to bacteria only (little/no side effects to humans)

Question 4

what do antibiotics target?

Answer 4

cell wall/ PG synthesis, DNA synthesis, RNA synthesis, protein synthesis

Question 5

how do we test for gram negative or gram positive bacteria?

Answer 5

a gram-stain test; will reveal cell wall differences

Question 6

examples of gram positive bacteria?

Answer 6

staphylococci, streptococci, enterococci; they have a thick layer of PG chains in their cell wall

Question 7

examples of gram negative bacteria?

Answer 7

E.coli, pseudomonas, salmonella - they have a thin layer of PG chains

Question 8

why are antibiotics that target PG biosynthesis not as effective against gram negative bacteria?

Answer 8

because gram negative bacteria only have a thin layer of PG chains in their cell wall

Question 9

examples of antibiotics that target cell wall/ PG biosynthesis?

Answer 9

b lactam antibiotics (penicillin, cephalosporin, carbapenems) and vancomycin

Question 10

how to b-lactam antibiotics kill bacteria?

Answer 10

they disrupt PG synthesis leading to autolysis (absence of a cell wall). they are bactericidal - kill bacteria

Question 11

describe b-lactam resistant bacteria

Answer 11

resistant bacteria species produce b-lactamase; a secreted enzyme that inactivates antibiotics by breaking down their b-lactam ring

Question 12

describe vancomycin

Answer 12

an antibiotic that targets the cell wall/ PG biosynthesis. it inhibits cell wall synthesis and precludes peptidyl bridges. associated with allergic reactions

Question 13

examples of antibiotics that target the 30S subunit of protein synthesis?

Answer 13

tetracylcline, doxycycline, aminoglycosides (gentamycin, streptomycin, tobramycin

Question 14

examples of antibiotics that target the 50S subunit of protein synthesis?

Answer 14

macrolides (erythromycin, clarithromycin) and chloramphenicol

Question 15

antibiotics that inhibit DNA and RNA biosynthesis?

Answer 15

DNA- fluoroquinolones. RNA - rifampicin

Question 16

sulphonamide, trimethoprim - describe these antibiotics?

Answer 16

synthetic antibiotics used to inhibit folic acid synthesis of bacteria

Question 17

which antibiotic inhibits bacterial RNA polymerases?

Answer 17

rifampicin

Question 18

what happens if their is an absence of functional ribosomes?

Answer 18

no protein synthesis

Question 19

describe amingoclycosides?

Answer 19

broad spectrum antibiotics such as; gentamycin, streptomycin, tobramycin - target protein biosynthesis

Question 20

describe macrolides?

Answer 20

broad spectrum antibitoics such as; erythromycin and clarithromycin - target protein biosynthesis