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Pharm Final > ABs : inhibitors of cell wall synthesis > Flashcards

ABs : inhibitors of cell wall synthesis Flashcards

1
Q

A AB that inhibit cell wall synthesis is only bactericidal when? do these ABs affect humans cells, why?
What microbe is intrinsically resistant to cell wall synthesis inhibitors?

A

Bactericidal ONLY when bacteria are growing
Do not effect humans cells bc human cells have no cell wall
Resistant= Mycoplasma (no cell wall) and L forms of bacteria (no cell walls)

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2
Q

Penicillin will not work against Mycoplasma and L forms of bacteria why?

A

Bc mycoplasma and L form bacteria do NOT have cell walls

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3
Q

What AB inhibits the first step of cell wall synthesis: L ala to D ala and linkage of two Dala.
This AB is used for what?

A

cycloserine

2nd line tx for TB

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4
Q

The 5 step of cell wall synthesis: sugar peptide added to peptidoglycan strands via peptidoglycan synthase is prevented by what AB

A

Bacitracin binds to the isoprenyl phosphate thus preventing it from carrying a sugar peptide to the cell membrane

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5
Q

How does Vancomycin prevent cell wall synthesis?

A

Vancomycin prevents cell wall synthesis by preventing transfer of sugar pentapeptide from carrier molecule to growing peptidoglycan chain : inhibition of peptidoglycan synthase and inhibition of cross linking of peptidolglycans

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6
Q

How do B lactams (ie penicillin) inhibit cell wall synthesis

A

B lactam act by binding to various penicillin binding proteins (PBPs) and inhibiting transpeptidation reaction

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7
Q

what is the specificity of B lactam due to?

How doe resistance to B lactams form?

A

B lactams specificity due to structural similarity w D-Ala dipeptide
resistance of B lactams comes from production of B lactamases which break the B lactam ring

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8
Q

What are the 4 ABs that are considered B lactams?

A

penicillins, cephalosporins, monobactams, carbapenems

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9
Q

What is the MoA of Penicillins?

Are penicillins cidal or static?

A

Penicillins mimic the D-ala-D- ala structure of pentapeptide on peptidoglycan and ties up transpeptidases
Penicillins are bactericidal!

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10
Q

what are naturally occurring penicillins effective against?
What are the 2 naturally occurring penicillins?
narrow or broad spectrum?

A

Penicilli G and V - narrow spectrum

they are effective against streps, many anaerobes, enterococcus, a few gram negative

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11
Q

what are Penicillin G and V not effective against?

A

Gram negative bacteria like E coli and Klebsiella

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12
Q

What are narrow spectrum penicillins that are active again staph and strepococci?

A

Anti- Staphlococcal (B lactamase resistant) penicillins

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13
Q

what are examples of B lactamase resistant penicillins?

A

Nafcillin, Oxacillin, Cloxacillin,

All end in cilin!

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14
Q

Resistance to penicillin has been acquired thru Methicillin resistant S aureus and methicillin resistant S epidermis what are these two phenotypes known as

A

MRSA and MRSE

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15
Q

All beta lactam drugs exhibit what type of resistance?

A

MRSA

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16
Q

What are amino penicillins? broad or narrow? B lactamase resistant or not? effective against?

A

Amino penicillins= ampicillin, and Amoxicillin
Broad spectrum,
effective against streps, enterococci and some gram neg
NOT B lactamase resistant!

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17
Q

What are Ampicillin and Amoxicillins considered?

what are they not effective against?

A

Amino penicillins!

NOT effective Pseudomonas aeruginosa

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18
Q

What are the 3 anti- pseudomonal penicillins?
broad or narrow spectrum?
effective against what

A

anti pseudomonal penicillins= carbenicillin, piperacillin, ticarcillin
EXTENDED spectrum
effective against pseudomonas aeruginosa, streps, enterobacteriaceae and many gram negs

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19
Q

clinical uses of penicillins

A

streps, pneumoniae, haemophilus infections (meningitis, epiglotitis)
STDs - syphilis
UTIs

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20
Q

Describe the 4 drug resistance scenarios facing penicillins and the bacteria associated with each

A
  1. B lactamase (gram + and gram -)
    2 altered PBPs: MRSA and S pneumoniae
  2. Altered Porins - gram -
  3. INC efflux
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21
Q

MRSA resistance bacteria are associated with what resistance factor?

A

Altered PBPs

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22
Q

when does one take penicillins and why

A

take penicillin before eating bc food dec oral absorption

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23
Q

penicillin
distribution: CNS Or not?
Excretion:
Toxicity:

A

Penicillins do NOT easily cross BBB but inflammation of meninges INC CSF entry. excreted really
Mild toxicities but direct toxic effects on kidney and some hypersensitivity rxns

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24
Q

What is the special note about classification of Penicillins?

A

Penicillins are TIME DEPENDENT ABs- so concentrations must be maintained for bacterial killing

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25
Q

Cephalosporins
cidal or static?
MoA

A

Cephalosporins are CIDAL

MoA: inhibitor of bacterial cell wall synthesis, but generally B lactamase resistant!

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26
Q

As one goes along the generations of 1 to 4th gen cephalosporins what is the general trend of their spectrum of action

A

as you inc generation the cephalosporin becomes more active against Gram neg but less effective against gram pos (especially against staph)
so 1st generation best against gram + but least against gram -
4th gen best against gram neg but worst against gram pos
each generation gets better spectrum of activity

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27
Q

1st generation cephalosporins include what AB?

effective against what? given how?

A

cefazolin = 1st gen cephalospin give IV or IM effective against gram +

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28
Q

3rd generation cephalosporins include what? most effective against what?

A

3rd gen cephalosporins= Ceftazidime, ceftriaxon

most effective against gram negative

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29
Q

what is the only 3rd gen cephalosporin effective against Pseudomonas?

A

Ceftazidime = Pseudomonas = 3rd gen!

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30
Q

4th generation cephalosporins include what?

A

Cefepime, Ceftolozane

31
Q 
Cephalosporin 
absorption
distribution
metabolism
toxicity
A 
absorption= oral and parenteral
distribution: 3rd and 4th gens cross BBB
metabolism: none
excreted like penicillins really
toxicity: better tolerated than penicillins, low tox
32
Q

What B lactam has a broad spectrum and is used against gram - and gram + bacteria? what drug is under this class

A

Carbapenems = Imipenem

33
Q

describe the interaction between carbapenems and B lactamase

A

Carbapenems are resistant to B lactamase

34
Q

what is the interaction between Imipenem and gram negative bacteria

A

imipenem binds well to PBP 1 and PBP2 of gram - bacteria especially effective against pseudomonas and Acinetobacter

35
Q

what are carbapenems (imipenem) reserved for

A

carbapenems are used ONLY for serious nosocomial infections - very restricted!

36
Q

Carbapenems route of admin

what is administered with carbapenems to increase their half life and block hydrolysis in renal tubules

A

Carbapenems are IV Only! admin with Cilastatin to INC half life

37
Q

What is a narrow spectrum AB that is used for serious nosocomal gram negative infections?

A

Monobactams

38
Q

What is Monobactams effective against?

A

Monobactams are effective against Gram negatives including pseudomonas aeruginosa

39
Q

What are Monobactams not effective against?

A

GRAM POSITIVE!

MONOBACTAMS GRAM NEG ONLY!

40
Q

What are the 3 B lactamase inhibitors that inactivate B lactamase?

A

Clavulanic acid, sulbactam, tazobactam

41
Q

What does Clavulanic acid, Sulbactam, and Tazobactam do?

A

Clavulanic acid, Sulbactam, and Tazobactam are inhibitors of B lactamase, binding irreversibly to serine active site

42
Q

What are Clavulanic acid, Sulbactam, and Tazobactam used for clinically?

A

used in combo with B lactam ABs to extend spectrum.

Amoxacillin + Clavulanate for Oral and IV use

43
Q

What is a large tricyclic glycopeptide from Streptomycin orientalis?
what 2 drugs fall under this?

A

Vancomycin
Teicoplanin
Telavancin

44
Q

MoA of Vancomycin (teicoplanin and telavancin)

A

Vancomycin binds to carboxyl terminus of D ala D ala inhibiting peptidoglycan synthase thus inhibiting transpeptidation crosslinking

45
Q

Is Vancomycin static or cidal?

A

Vancomycin is CIDAL! but resistance is making it more static

46
Q

Resistance to Vancomycin is rampant, why?

A

Vancomycin binds to D ala D ala and bacteria are changing this sequence to D ala D Lac or to D ala D see leading to VRE and VRSA

47
Q

What is the spectrum of Vancomycin and what is it used against?

A

Vancomycin is NARROW! used against GRAM + staphyococci, strep, E faceless,

48
Q

what is Vancomycin not effective against!

A

GRAM Negative!

49
Q

what is Vancomycin used often to treat?

A

Methicillin resistant staphylococci (MRSA)

50
Q

clinical use of Vancomycin

A

MRSA, enterococci, meningitis

51
Q

severe C difficile infection from overuse of penicillin is best treated how

A

SEVERE colitis = Vancomycin

52
Q

for moderate C difficile infection (moderate pseudomonas colitis) (moderate Colitis) what is used for TX?

A

Metronidazole or Fidaxomicin

53
Q

Vancomycin route of admin, metabolism, excretion

A

Vancomycin given orally or by IV, no metabolism, excreted renally

54
Q

what is the Toxicity associated with Vancomycin?

other toxicities?

A

RED man syndrome:

also hearing loss

55
Q

what is the MoA of bacitracin

A

Bacitracin binds to isoprenyl phosphate lipid carriers inhibiting dephosphorylation and utilization

56
Q

Bacitracin spectrum and effectiveness

A

Bacitracin used against Gram + cocci, some gram neg

57
Q

what specific infections are bacitracin used for

A

superficial and ophthalmic infections

58
Q

what is used to treat penicillin resistant S pneumoniae

A

3rd and 4th generation quinolones

59
Q

what is used to treat MRSA

A

Vancomycin

60
Q

what are 2 cell membrane disrupting AB

A

daptomycin and polymyxins

61
Q

what are polymyxins effective against?

A

POLYMIXIN= GRAM - !!

62
Q

what is a type E polymyxin that accumulates in outer portion of cell membrane

A

Colistin

63
Q

are Polymyxins cidal or static

A

Polymyxins are CIDAL!

64
Q

MoA of Polymyxins

A

Polymyxins act as cationic detergent disrupting cell membrane of gram NEG.

65
Q

what are Polymyxins NOT effective against?

A

Polymyxins are not effective against GRAM + bacteria!

66
Q

what is used to treat pan resistant, gram neg infections including pseudomonas and acinetobacter?

A

Polymyxin = Colistin

67
Q

Polymyxins used to treat what

A

Polymyxin useful against pseudomonas infections in ears, eyes by topical

68
Q

Polymyxin is what kind of toxicity drug

A

Polymyxin is DOSE RELATED!

69
Q

resistance of Polymyxin

A

Polymyxin resistance is rare! altered LPS anionic lipid content

70
Q

Daptomycin is a cidal or static drug, acting on what

A

Daptomycin is CIDAL acting on disrupting cell membrane thus disrupting DNA, RNA and protein synthesis

71
Q

what is Daptomycin useful against

A

GRAM POSITIVE ONLY! = DAPTOMYCIN

72
Q

What is special about the usefulness of Daptomycin?

A

Daptomycin useful against VRE, and MRSA

73
Q

where is daptomycin not useful?

A

DAPTOMYCIN NOT useful for Lung infections

74
Q

what is Daptomycin considered

A

Daptomycin= Concentration dependent drug!

Pharm Final (13 decks)

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