Antibiotics 1

Question 1

what is an antibacterial?

Answer 1

substances used to disinfect non-living surfaces

Question 2

what are the gram positive rods that produce antibiotics?

Answer 2

bacillus subtilis and paenibacilus polymyxa

Question 3

what other drugs produce antibiotics?

Answer 3

streptomyces, cephalosporin and penicillium

Question 4

what are antibiotics classified by?

Answer 4

their mechanism, chemical structure, spectrum of activity

Question 5

what are some of the target sites of antibiotics?

Answer 5

cell wall synthesis, protein synthesis, nucleic acid action and injury to a plasma membrane

Question 6

what drugs inhibit cell wall synthesis?

Answer 6

pencillins, cephalosporins, bacitracin and vancomycin

Question 7

what does erythromycin, tetracyclines and streptomycin do?

Answer 7

cause inhibitor of protein synthesis

Question 8

what do quinolone do?

Answer 8

cause inhibition of nucleic acid replication and transcription

Question 9

what does rifampin do?

Answer 9

cause inhibition of protein synthesis

Question 10

what drugs cause injury to the plasma membrane?

Answer 10

polymyxin B

Question 11

what do beta lactams do?

Answer 11

effect cell wall construction

Question 12

what drugs inhibit protein synthesis?

Answer 12

ahminoglycosides, tetracyclines, lincosamine and macrocodes

Question 13

what are the desired properties of antimicrobials?

Answer 13

selectivity, broad spectrum

Question 14

what are the desired pharmacological properties?

Answer 14

non-toxic to host, good tissue distribution, low plasma-protein binding, no interference with other drugs

Question 15

what is selectivity toxicity?

Answer 15

kills harmful microorganisms without damaging the host

Question 16

how is selective toxicity achieved?

Answer 16

the target sites of the drugs are specific to the microorganism

Question 17

what is the therapeutic index?

Answer 17

ratio of toxic dose to therapeutic dose

Question 18

what is bactericidal activity?

Answer 18

antibiotics that target bacterial cell wall or interfere with essential enzymes

Question 19

what is bacteriostatic activity?

Answer 19

slows the growth of bacteria

Question 20

what factors effect concentration?

Answer 20

dose, route of administration, absorption, extent of protein binding, rate of metabolism, rate of excretion

Question 21

what must the concentration of the antibiotic be in order to be effective?

Answer 21

must reach a concentration that is above the bacteriums MIC to be effective

Question 22

what is the mechanism of action of polymyxins?

Answer 22

to selectively act on membranes rich in phosphatidylethanolamine

Question 23

what bacteria is polymyxins effective on?

Answer 23

gram negative rods including pseudomonas

Question 24

what kind of bacteria is polymyxins not effective to?

Answer 24

gram positive bacteria

Question 25

what are the pharmacodynamic features of polymyxin?

Answer 25

not absorbed after oral administration because of multiple positive charges, cross membranes poorly, not well distributed and eliminated via kidneys

Question 26

what is a common clinical use of polymyxin?

Answer 26

used in topical triple antibiotic locations with neomycin and bacitracin

Question 27

why is polymyxin rarely used systemically?

Answer 27

highly toxic

Question 28

what are the adverse reactions of polymyxin?

Answer 28

nephrotoxicity and neurotoxicity

Question 29

what are the chemical structural features of polymyxin?

Answer 29

has hydrophobic tail ands a cyclic peptide

Question 30

how can targeting of cell walls help provide a more specific target?

Answer 30

mammalian cells do not have a cell wall so it provides a target for chemotherapy

Question 31

what antibiotics target the cell wall?

Answer 31

beta lactams, cephalosporins, vancomycin and bacitracin

Question 32

what antifungals target the cell wall?

Answer 32

cilofungin interferes with biosynthesis of beta gluten in fungal cell wall

Question 33

what does cycloserine do?

Answer 33

inhibits peptidoglycan precursor formation inside the cell

Question 34

what does bacitracin and vancomycin do?

Answer 34

inhibits transport and peptidoglycan formation in the cell membrane

Question 35

what do penicillin and cephalosporins inhibit?

Answer 35

cross linking of peptodoglycans that occurs outside the cell

Question 36

what steps of cell wall synthesis does cycloserine inhibit?

Answer 36

d-alanyl-d-alanyl synthesis and d-alanine-d-alanine ligase

Question 37

what is cycloserine used to treat?

Answer 37

tuberculosis

Question 38

what is undecaprenyl phosphate?

Answer 38

a carrier required during peptidoglycan synthesis

Question 39

what does bacitracin do to prevent peptidoglycan synthesis?

Answer 39

inhibits the dephospho rylation of undecaprenyl phosphate to produce the carrier needed for synthesis

Question 40

what does vancomycin bind to?

Answer 40

the d-ala-d-ala terminus of the cell wall precursor units

Question 41

how does vancomycin prevent cell wall synthesis?

Answer 41

binds to the terminus and prevents cross-linking and polymerisation of peptidoglycan

Question 42

what kind of spectrum does vancomycin have?

Answer 42

narrow

Question 43

what are the clinical uses of vancomycin?

Answer 43

MRSA

Question 44

how is some bacteria able to be resistant to vancomycin?

Answer 44

vancomycin cannot bind to the D-lactate residues and so peptide chains form stable cross-links

Question 45

what is the chemical structure of cephalosporins?

Answer 45

a beta lactam cyclic amide ring attached to a 6 membered ring

Question 46

what is the chemical structure of penicillin and panems?

Answer 46

4 membered cyclic amide ring attached to a 5 membered ring

Question 47

what is the structure of a monobactam?

Answer 47

a 4 membered cyclic amide ring attached to no other rings

Question 48

what do betalactams inhibit?

Answer 48

transpeptidase reaction

Question 49

what is the substrate forget lactamases?

Answer 49

penicillin binding protein

Question 50

what is the transpeptidase reaction?

Answer 50

catalysing of the cross linking of the bacterial peptidoglycan during cell wall synthesis

Question 51

what is a PBP?

Answer 51

they create the cross links in the cell wall

Question 52

how might PBP's lead to antibiotic resistance?

Answer 52

altered PBP's may confer resistance to antibiotics

Question 53

what is penicillinase also known as?

Answer 53

beta lactamase

Question 54

what effect does penicillinase have on penicillin?

Answer 54

the beta lactam ring in active penicillin is broken open so that it becomes inactive