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Principles of Pharmacology > Antibiotics 1 > Flashcards

Antibiotics 1 Flashcards

1
Q

what is an antibacterial?

A

substances used to disinfect non-living surfaces

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2
Q

what are the gram positive rods that produce antibiotics?

A

bacillus subtilis and paenibacilus polymyxa

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3
Q

what other drugs produce antibiotics?

A

streptomyces, cephalosporin and penicillium

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4
Q

what are antibiotics classified by?

A

their mechanism, chemical structure, spectrum of activity

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5
Q

what are some of the target sites of antibiotics?

A

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

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6
Q

what drugs inhibit cell wall synthesis?

A

pencillins, cephalosporins, bacitracin and vancomycin

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7
Q

what does erythromycin, tetracyclines and streptomycin do?

A

cause inhibitor of protein synthesis

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8
Q

what do quinolone do?

A

cause inhibition of nucleic acid replication and transcription

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9
Q

what does rifampin do?

A

cause inhibition of protein synthesis

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10
Q

what drugs cause injury to the plasma membrane?

A

polymyxin B

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11
Q

what do beta lactams do?

A

effect cell wall construction

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12
Q

what drugs inhibit protein synthesis?

A

ahminoglycosides, tetracyclines, lincosamine and macrocodes

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13
Q

what are the desired properties of antimicrobials?

A

selectivity, broad spectrum

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14
Q

what are the desired pharmacological properties?

A

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

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15
Q

what is selectivity toxicity?

A

kills harmful microorganisms without damaging the host

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16
Q

how is selective toxicity achieved?

A

the target sites of the drugs are specific to the microorganism

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17
Q

what is the therapeutic index?

A

ratio of toxic dose to therapeutic dose

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18
Q

what is bactericidal activity?

A

antibiotics that target bacterial cell wall or interfere with essential enzymes

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19
Q

what is bacteriostatic activity?

A

slows the growth of bacteria

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20
Q

what factors effect concentration?

A

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

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21
Q

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

A

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

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22
Q

what is the mechanism of action of polymyxins?

A

to selectively act on membranes rich in phosphatidylethanolamine

23
Q

what bacteria is polymyxins effective on?

A

gram negative rods including pseudomonas

24
Q

what kind of bacteria is polymyxins not effective to?

A

gram positive bacteria

25
Q

what are the pharmacodynamic features of polymyxin?

A

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

26
Q

what is a common clinical use of polymyxin?

A

used in topical triple antibiotic locations with neomycin and bacitracin

27
Q

why is polymyxin rarely used systemically?

A

highly toxic

28
Q

what are the adverse reactions of polymyxin?

A

nephrotoxicity and neurotoxicity

29
Q

what are the chemical structural features of polymyxin?

A

has hydrophobic tail ands a cyclic peptide

30
Q

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

A

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

31
Q

what antibiotics target the cell wall?

A

beta lactams, cephalosporins, vancomycin and bacitracin

32
Q

what antifungals target the cell wall?

A

cilofungin interferes with biosynthesis of beta gluten in fungal cell wall

33
Q

what does cycloserine do?

A

inhibits peptidoglycan precursor formation inside the cell

34
Q

what does bacitracin and vancomycin do?

A

inhibits transport and peptidoglycan formation in the cell membrane

35
Q

what do penicillin and cephalosporins inhibit?

A

cross linking of peptodoglycans that occurs outside the cell

36
Q

what steps of cell wall synthesis does cycloserine inhibit?

A

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

37
Q

what is cycloserine used to treat?

A

tuberculosis

38
Q

what is undecaprenyl phosphate?

A

a carrier required during peptidoglycan synthesis

39
Q

what does bacitracin do to prevent peptidoglycan synthesis?

A

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

40
Q

what does vancomycin bind to?

A

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

41
Q

how does vancomycin prevent cell wall synthesis?

A

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

42
Q

what kind of spectrum does vancomycin have?

A

narrow

43
Q

what are the clinical uses of vancomycin?

A

MRSA

44
Q

how is some bacteria able to be resistant to vancomycin?

A

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

45
Q

what is the chemical structure of cephalosporins?

A

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

46
Q

what is the chemical structure of penicillin and panems?

A

4 membered cyclic amide ring attached to a 5 membered ring

47
Q

what is the structure of a monobactam?

A

a 4 membered cyclic amide ring attached to no other rings

48
Q

what do betalactams inhibit?

A

transpeptidase reaction

49
Q

what is the substrate forget lactamases?

A

penicillin binding protein

50
Q

what is the transpeptidase reaction?

A

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

51
Q

what is a PBP?

A

they create the cross links in the cell wall

52
Q

how might PBP’s lead to antibiotic resistance?

A

altered PBP’s may confer resistance to antibiotics

53
Q

what is penicillinase also known as?

A

beta lactamase

54
Q

what effect does penicillinase have on penicillin?

A

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

Principles of Pharmacology (12 decks)

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