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PR3151 > Bacterial Wall Synthesis Inhibitors > Flashcards

Bacterial Wall Synthesis Inhibitors Flashcards

1
Q

How does bacterial cell wall synthesis inhibitor work?

A

Binds to/near active site of transpeptidase/penicillin-binding protein (PBP) thus inhibiting crosslinking of peptidoglycan cell wall

For actively growing bacteria, cell wall weakened, causing increased intracellular osmotic pressure, leading to cell lysis

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2
Q

What are the types of BCWI?

A

Beta-lactam
Glycopeptide

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3
Q

What are the types of beta lactam?

A

Penicillin, carbepenem, cephalosporin, monobactam

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4
Q

What are the types of penicillins?

A

Natural penicillin
Penicillinase-Resistant Penicillin
Aminopenicillin
Anti-pseudomonas Penicillin

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5
Q

Examples of natural penicillin?

A

Penicillin G (IV)
Penicillin V (PO)

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6
Q

Which natural penicillin has good F?

A

Penicillin V

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7
Q

Syphilis caused by Treponema pallidum can be treated with which penicillin?

A

Penicillin G

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8
Q

What penicillin can be used against MRSA?

A

Penicillinase-resistant penicillin: cloxacillin

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9
Q

What bacteria does cloxacillin cover?

A

Only gram-positive (staphylococci)

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10
Q

What to take note of when taking cloxacillin?

A

Best taken on empty stomach

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11
Q

Why is cloxacillin penicillinase resistant?

A

Bulky side chain limits the accessibility of beta-lactamases to the catalytic site of action

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12
Q

Why are aminopenicillinases broad spectrum?

A

They have additional hydrophilic groups to penetrate gram-negative bacteria via porins

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13
Q

Are Amoxicillin and ampicillin effective against Pseudomonas?

A

No

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14
Q

Are Amoxicillin and Ampicillin effective against Klebsiella?

A

No

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15
Q

Can IV Amoxicillin and Ampicillin be used for CNS infection?

A

Yes

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16
Q

Ampicillin or Amoxicillin hss better oral absorption?

A

Amoxicillin

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17
Q

Does piperacillin cover MRSA?

A

No

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18
Q

Is piperacillin effective against pseudomonas?

A

Yes

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19
Q

How is piperacillin cleared?

A

70% renal

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20
Q

How does beta-lactamase inhibitors work?

A

Bind and inactivate irreversibly to serine beta-lactamase via covalent bonds to protect beta-lactams from catalysis by restructuring and permanently inactivating it.

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21
Q

What are the BL Combination drugs?

A

Augmentin PO/IV (Amoxicillin + Clavulanate)
Unasyn IV (Ampicillin + Sulbactam)
Zosyn IV (Piperacillin + Tazobactam)

22
Q

How does resistance to penicillin arise?

A
  1. Altered PBP with reduced affinity to penicillin ( MRSA: PBP2a)
  2. Production of penicillinase
  3. Decrease porin production –> decreased ability if Abx to enter cell, decr drug conc
  4. Efflux pumps
23
Q

Adverse rxns for penicillins

A
  1. Hypersensitivity (Stevens Johnson syndrome and toxic epidermal necrolysis) + anaphylaxis
  2. GI symptoms (NV, Clostridioides difficile-associated disease(CDAD))
  3. Neurotoxicity
24
Q

What are the different generations of cephalosporins?

A

1st gen: cefazolin IV, cephalexin PO
2nd gen: Cefuroxime PO
3rd gen: Ceftriaxone , Ceftazidime
4th gen: Cefepime
5th gen: Ceftriziprole, Ceftaroline

25
Q

Which cephalosporin has activity against Pseudomonas?

A

3rd gen: ceftazidime
4th gen: Cefepime

26
Q

What cephalosporin is effective against MRSA?

A

Ceftaroline

27
Q

What are the 1st and 2nd gen cephalosporins ineffective against?

A
  1. Pseudomonas
  2. Listeria Monocytogenes
  3. Atypicals (Mycoplasma, Chlamydia, Legionella spp.)
  4. MRSA
  5. Enterococcus spp.
28
Q

Which 3rd gen cephalosporin is effective aginst Pseudomonas?

A

Ceftazidime

29
Q

What can be used for vancomycin-ressistant S. Aureus?

A

Ceftaroline

30
Q

What can be used for Streptococcus pneumoniae?

A

Ceftaroline

31
Q

What are 3 advantages of later gen cephalosporins compared to 1st/2nd gen

A
  1. Greater resistance to beta-lactamase
  2. Greater gram-negative coverage due to increased affinity for transpeptidase
  3. Greater CNS penetration
32
Q

Which cephalosporin is cleared hepatically?

A

Ceftriaxone: 40% in bile

33
Q

What is IV incompatible with ceftriaxone?

A

Calcium-containing pdt (Ringer’s or Hartmann’s solution) –> Ca precipitate formation

34
Q

What is Carbepenems used for?

A

Extended spectrum beta-lactamase producing bacteria (gram-negative + anaerobic spp.)

35
Q

Imipenem is combined with ____, so that

A

Cilastatin

Cilastatin inhibits dehydropeptidase 1 (DHP1) in the brush border of proximal renal tubule to prevent rapid hydrolysis of imipenem so that more of active form is recovered.

36
Q

Which carbepenum cannot be used against P. aeruginosa and enterococcus spp.?

A

Ertapenem

37
Q

What does imipenem and meropenem cover?

A
  1. P. Aeruginosa
  2. Enterococcus spp.
  3. Staphylococci (incl. penicillinase-producing strains)
  4. Streptococci (incl. penicillinase-producing strains)
  5. Anaerobes (Bacteriodes fragilis)
38
Q

When is carbepenem used?

A

Mod-severely ill patients with nosocomial infections
Usually in hospitals

39
Q

Can carbepenem be used for MRSA?

A

No

40
Q

Is there cross allergy between carbepenem and penicillin?

A

Yes

41
Q

What class of drug is aztreonam?

A

Beta lactam: Monobactam

42
Q

What does Aztreonam cover?

A

Gram negative only
- enterococcus
- p. Aeruginosa
- Haemophillus influenzae
- Neisseria gonorrhoeae
- Escherichia coli
- Klebsiella pneumoniae

43
Q

How is Aztreonam administered?

A

IV/IM

44
Q

Does monobactam cause cross allergy with penicillin?

A

Not likely

45
Q

How does vancomycin work?

A

Vancomycin binds with high affinity to D-Ala- D-Ala terminus of pentapeptide of NAM component od peptidoglycan and interferes with transglycosylation of cell wall precusor units, inhibiting cell wall synthesis.

46
Q

What does vancomycin cover?

A

Gram positive only
Due to its large molecular size(1500kDa), which limits its ability to penetrate outer membrane of gram negative bacteria

47
Q

How is vancomycin administered?

A

IV
PO (poor F) for Clostridioides difficiles associated disease

48
Q

How is vancomycin cleared?

A

Renal

49
Q

ADR of vancomycin

A
  1. Thrombophlebitis with fever and chills
  2. Red-neck/ Red Man Syndrome (prevented by prolonging infusion to 1-2hrs)
  3. Nephrotoxicity
  4. Ototoxicity
50
Q

What BCWI can be used against MRSA?

A
  1. Ceftobizime
  2. Ceftaroline
  3. Vancomycin
51
Q

Why do 3rd gen cephalosporins require antimicrobial stewardship?

A

They drive ESBL production

52
Q

What are first line agents for MSSA bateremia?

A

Cloxacillin, cephalexin

PR3151 (12 decks)

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