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Pharm I > Penicillins > Flashcards

Penicillins Flashcards

1
Q

what does Cell Wall prevent cell from?

A

osmotic rupture b/c cell is hyperosmolar —hopefully remembering physio

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2
Q

what is a Peptidoglycan cell wall?

A

it is large, covalently linked sacculus surrounding the bacterium

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3
Q

what are peptidoglycan composed of?

A
  1. backbone of two alternating sugars, N-acetylglucosamine and N-acetylmuramic acid
  2. a chain of four amino acids that are linked to NAM
  3. a peptide bridge that cross-links the tetrapeptide chains (D-gln to D-ala)
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4
Q

what are the points at which abx interfere w/CW synth?

A
  1. Transglycosylation-joining NAM-NAG
  2. transpeptidation-cross links pentapeptides
  3. NAG reduction to NAM
  4. transport across the inner membrane
  5. AA mimicry-pentapeptide chain
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5
Q

at what point during CW synth. penicillin binding proteins (BPBs) have enzymatic action?

A

enzymatic action on transglycosylation and transpeptidation

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6
Q

what is MOA of Fosfomycin?

A

inhibit one of the first steps in synth of peptidoglycan

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7
Q

what is MOA of Cycloserine?

A

structural analog of the AA D-alanine

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8
Q

what is MOA of Bacitracin?

A

inhibits activation of lipid carrier that moves water soluble cytoplasmic peptidoglycan subunits thru membrane

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9
Q

what is MOA of Glycopeptides (vancomycin)?

A

sterically inhibit the addition of subunits to the peptidoglycan backbone

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10
Q

what is MOA of ß-lactam abx?

A

prevent the cross-linking rxn called transpeptidation

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11
Q

transpeptidation is performend by what?

A

transpeptidases or PBPs

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12
Q

all abx inhibiting bacterial CW synth are:

a. bacticidal
b. bacteriostatic

A

A.CIDAL– cause cell death due to OSMOTIC LYSIS

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13
Q

True or False?

Loss of CW integrity in presence of abx is bacteria’s own fault.

A

True. b/c it is due to bacteria’s own CW remodeling enzymes that cleave peptidoglycan bonds in the normal course of cell growth.

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14
Q

what are bacteria’s remodeling enzyme called?

A

autolysins

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15
Q

True or False?

autolysins are not so guilty.

A

true. bc they don’t know that CW inhibitors are present…so autolysis proceeds without normal cell-wall repair leading to weakness and lysis.

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16
Q

what is MOA of protein synth inhibitors like chloramphenicol?

A

PREVENT the action of the ICWS

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17
Q

what is ICWS?

A

inhibitors of cell wall synthesis

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18
Q

ICWS are active against what?

A

G+, pseudomonas aeruginosa

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19
Q

True or false?

ICWS are acid and penicillinase resistant.

A

True. so oral absorption

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20
Q

Name 4 ß-lactam ICWS.

A

Penicilins
Caphalosporins
monobactams
carbapenems

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21
Q

Name 4 NOT ß-lactam ICWS.

A

vancomycin
phosphomycin
bacitracin
cycloserine

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22
Q

can you name natural penicillins?

A

Pen G
Pen V
P Pen G
B Pen

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23
Q

would you name Penicillinase resistant penicilines? at least the prototype?

A

Nafcillin
Docloxacillin
Oxacillin
Methicillin

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24
Q

can you name the prototype for Extended spectrum penicillin?

A

Ampicillin
Amoxicillin
Bacampicillin

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25
Q

what is the prototype for Antipseudomonal penicillins?

A

Piperacillin
Ticarcillin
Mezlocillin
Carbenicillin

26
Q

what are 4 categories of Penicillins?

A

Natural penicillins, penicillinase resistant, extended spectrum, antipseudomonal

27
Q

Natural Penicillins have HIGHEST activity against?

A

G+ including G+ anaerobics.

28
Q

do natural pens have G- coverage?

A

yes. some

29
Q

are natural pens inactivated by ß-lactamase?

A

YES. inactivated by ß-lactamase (penicillinase): not effective against stains of S aureus

30
Q

how is Penicillinase-resistant Pens activity against G+?

A

LOWER ACTIVITY against G+

31
Q

what is MRSA’s mechanism of resistance?

A

not a/w ß-lactamse

Produces alternate PBP which decrease the affinity of ß-lactam abx to PBP

32
Q

how is extended spectrum pens’ G+ and G-coverage?

A

LOWER G+ coverage
EXTENDED G- coverage
resistance develop frequently

33
Q

what is antipseudomonal pens’ spectrum?

A

spectrum: bacteria covered by the extended spectrum pens plus some additional enteric G- bacilli

34
Q

Do natural pens have antipseudomonal activity?

A

Nope.

35
Q

how are natural pens eliminated?

A

eliminated by active transport in kidney (probenecid)

36
Q

how is natural pens CNS penetration?

A

poor.

37
Q

which natural pen can be given orally?

A

Pen V because it is acid resistant.

38
Q

are penicillinase resistant pens resistant to penicillnase?

A

YES!…duh!!

39
Q

do penicillinase resistant pens have G- coverage?

A

some.

40
Q

can penicillinase resistant pens be given orally?

A

only some are acid stable and highly protein bound.

41
Q

what are penicillinase resistant pens DOC for ?

A

MSSA

42
Q

how are penicillinase resistant pens excreted?

A

Hepatic metabolism and renal excretion

43
Q

can ß-lactam be used to treat MRSA?

A

NO ß-lactam can be used to treat MRSA except ceftaroline

44
Q

do extended spectrum pens have antipseudomonal activity?

A

NO antipseudomonal activity

45
Q

are extended spectrum pens susseptible to ß-lactamase?

A

susceptible to ß-lactamase

46
Q

can extended spectrum pens be given orally?

A

acid resitant–so oral

47
Q

how are extended spectrum pens excreted?

A

urinary excretion

48
Q

what are extended spectrum pens DOC for?

A

Lysteria infection

49
Q

Rash due to what abx is not hypersensitivity?

A

ampicillin

50
Q

what is the major use of antipseudomonal pens?

A

major use: pseudomonas aeruginosa and acinetobacter

51
Q

are antipseudomonal pens susceptible to ß-lactamase?

A

yes. susceptible to ß-lactamase

52
Q

can antipseudomonal pens be given orally?

A

NOPE! acid sensitive

53
Q

how are antipseudomonal pens excreted?

A

renal excretion

54
Q

how should we use antipseudomonal pens to prevent resistance?

A

must be used in combination w/aminoglycosides to prevent resistance.

55
Q

what is the purpose of ß-lactamase inhibitors?

A

b/c most of pens are susceptible to ß-lactamase, addition of ß-lactamase inhibitors extends the spectrum of these agents

56
Q

what are the down sides of ß-lactamase inhibitors?

A

however not all ß-lactamases are inhibited by these products
and bacteria may develop resistance independent upon ß-lactamase production such altered PBP production, MRSA

57
Q

what are some of ß-lactamase inhibitors?

A

clauvulanic acid, sulbactam, tazobactam

58
Q

what are some of the pens that ß-lactamase inhibitors are added to?

A

ampicilin, amoxicillin, ticarcillin or piperacillin

59
Q

what are some mechanisms of bacterial resistance for pens?

A
  1. inactivation by bacterial ß-lactamase
  2. decreased permeabilty in G-
  3. alterations in PBPs so pens cannot bind like in MRSA
  4. autolytic enzymes not being activated so forming tolerant such Listeria and staph.
  5. lack of cell wall
60
Q

what are some toxicity of pens?

A

allergy all form—remember ampicillin rash is not an allergy
electrolyte imbalance
GI problems
superinfections

61
Q

penicilins pharmacokinetic summary:

A 
good tissue penetration
poor CNS penetration
mostly renal elimination
filtration and tubular excretion
probenecid inhibits renal elimination

Pharm I (7 decks)

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