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Antimicrobials > Bact cell wall synth inhibitor > Flashcards

Bact cell wall synth inhibitor Flashcards

1
Q

Name 2 classes of bacterial cell wall synthesis inhibitors.

A

Beta-lactams, Glycopeptide

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2
Q

Beta lactams bind to the active site of which enzyme?

A

Transpeptidase (penicillin binding protein)

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3
Q

Effect of beta lactams

A

Bacteriocidal on actively growing cells

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4
Q

Name 4 types of beta lactams

A

Penicillins, cephalosporins, carbapenems, monobactam

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5
Q

Name the 4 classes of penicillins

A
  1. natural penicillins (Pen G and Pen V),
  2. penicillinase resistant penicillins (cloxacillin, flucloxacillin),
  3. aminopenicillins (amoxicillin, ampicillin),
  4. antipseudomonal penicillins (piperacillin)
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6
Q

Which natural penicillin is administered parenterally?

A

Penicillin G

vs V (phenoxymethylpenicilin) oral - more acid stable

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7
Q

3 types of Penicillin G

A

Potassium

Procaine
Benzathine
- slow release

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8
Q

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

A

Penicillin G

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9
Q

Natural penicillin indications

A
  1. gram +ve except staph
  2. gram -ve (meningococcus, gonorrhea)
  3. Treponema pallidum (syphilis)–G
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10
Q

What’s IV aq pencilin G used for?

A

Inflamed meninges– greater CSF penetration

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11
Q

Are natural penicillins commonly used against Staphylococcus aureus?

A

No

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12
Q

How does methicillin sensitive Staphylococcus aureus acquire resistance against the natural penicillins?

A

They produce penicillinases

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13
Q

Which class of penicillin is commonly used against methicillin sensitive Staphylococcus aureus?

A

Penicillinase resistant penicillin

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14
Q

Penicillinase resistant penicillin – 3 drugs

A

Cloxacillin
Flucloxacillin
Oxacillin

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15
Q

Indications of Penicillinase resistant penicillin

A
  1. Staph
  2. Ineffective against gram -ve
  3. if strain susceptible to penicillin G, shld use (as PRP will be less effective in this case)
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16
Q

Why Penicillinase resistant penicillin ineffective against gram -ve

A

Bulky side group
which limits pencillinase access to catalytic site
limits entry to gram -ve bact

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17
Q

Which bacteria is cloxacillin effective against?

A

Methicillin Sensitive Staphylococcus Aureus (MSSA)

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18
Q

So since PRP cannot target gram -ve, what is used?

A

Aminopenicillin (broad spectrum penicillins)

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19
Q

List 2 drugs under this class

A

Ampicillin

Amoxicillin

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20
Q

Which of the aminopenicillins (amoxicillin or ampicillin) has better oral absorption?

A

Amoxicillin

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21
Q

Why aminopenicillins can target gram -ve?

A

Addnal Hydrophilic group– allow penetration

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22
Q

Indications of aminopenicillins

A

Non beta-lactamase producing strains of gram -ve/+ve bacteria

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23
Q

Aminopenicillins does not cover…

A

Pseudomonas & klebsiella

nosocomial infections

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24
Q

So you need…

A

Extended spectrum penicillins (antipseudomonals penicillins)

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25
Q

Drug under this class

A

Piperacillin

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26
Q

How is piperacillin administered?

A

IV

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27
Q

Indications of piperacillin

A
  1. Pseudomonas, proteus, klebsiella
  2. Anaerobes
  3. Non beta-lactamase gram +ve : S pyogenes + Enterococcus
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28
Q

Which 2 types of penicillins are used w beta-lactamase inhibitors?

A

Broad spectrum- aminopenicillins (ampicillin/amoxicillin)

Extended spectrum- antipseudom p (piperacillin)

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29
Q

MOA of beta-lactamase inhibitors (BLI)

A

Clavulanic acid – suicide inhibitor covalent bonds w beta-lactamase & restructures it

Sulbactam & tazobactam- irrev bind to active site

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30
Q

Name 3 beta lactams- beta-lactamase inhibitor combination drugs.

A
  1. Augmentin (Amoxicillin + clavulanic acid)
  2. Unasyn (ampicillin + sulbactam)
  3. Zosyn (piperacillin + tazobactam)
31
Q

How are all penicillins cleared by?

A

Renal clearance

32
Q

Name a microbe that commonly causes nosocomial infections and is resistant to all penicillins.

A

MRSA (methicillin resistant Staphylococcus aureus)

33
Q

Mechanism of resistance to penicillin

A
  1. PBP2a (altered transpeptidase reduced affinity for penicillins)– MRSA
  2. beta-lactamase (hydrolysis of b-l rings)
  3. Increased efflux pumps
  4. Decreased porins (for penicillin influx)
34
Q

Name at least 2 penicillins related life-threatening allergic reactions.

A
  1. Hypersensitivity (Anaphylaxis, SJS, TEN)
  2. CDAD (clostridium difficile associated diarrhea)- BSP amox (augm)/amp
  3. Neurotoxicity (esp in renal imp–> high doses seizures)
  4. Hepatic toxicity (PRP ox/fluclox/cloxacillin)
  5. Anosmia
35
Q

Str of cephalosporin

A
  1. modification at position 7 of BL ring associated w alteration in antibacterial activity
  2. Sub at position 3 of dht ring alters metab & pk
36
Q

Which generation of cephalosporins does cefazolin and cephalexin belong to?

A

First generation

37
Q

What’s the second generation cephalosporin?

A

Cefuroxime

38
Q

Which generation of cephalosporins are primarily administered orally?

A

First & second generation EXCEPT cefazolin can IV

39
Q

How are the 3rd, 4th and 5th generation cephalosporins administered?

A

Parenterally

40
Q

1st to 4th generation are ineffective against?

A
  1. Listeria monocytogenes,
  2. Atypicals (Mycoplasma, Chlamydia, Legionella spp.),
  3. MRSA, and
  4. Enterococcus species
41
Q

What are the drugs under 3rd, 4th and 5th generation cephalosporins?

A

3rd- ceftriaxone, ceftazidime
4th- cefepime
5th- ceftobiprole, ceftaroline

42
Q

Which cephalosporins could be used for pseudomonas?

A

Third generation – Ceftazidime

Fourth generation - Cefepime

& 5th gen

43
Q

Which generation of cephalosporins has coverage against MRSA?

A

Fifth generation (ceftobiprole, ceftaroline)

44
Q

Indications for cephalosporin

A

First gen- Gram +ve: staph & strep
**(except pencillinase producing strep + MRSA)

Second gen- 1st&2nd g Cannot be used for enterococcus/pseudomonas

Third gen- Enteroc, Pseud, N. gonorrhea & gram +ve
** (except Bacteroides spp.

45
Q

How are most cephalosporins cleared?

A

Renal clearance

46
Q

How is ceftriaxone cleared?

A

Hepatic clearance (40% bile)

47
Q

What should ceftriaxone not be mixed with?

A

Ca2+ containing soln (eg. Hartmann’s / Ringer’s)

48
Q

Name 3 advantages the third generation and fourth generation cephalosporins have over the first and second generations.

A
  1. Higher activity against Gram-negative bacteria
  2. Greater resistance against the beta-lactamase producing strains
  3. Greater CSF penetration
49
Q

What are the adverse reactions to cephalosphorins?

A
  1. hypersensitivity
  2. GIT - diarrhea (esp oral ceph) + CDAD
  3. Thrombophlebitis
50
Q

What are the adverse reactions to carbapenems?

A
  1. GIT-related (N/V, diarrhea)
  2. Neurotoxicity (at high blood [ ])
  3. Rashes
  4. Cross hypersensitivity w pencillin
51
Q

What are carbapenems prescribed for?

A

Commonly used against extended spectrum beta-lactamase (ESBL) producing bacteria

Gram -ve & anaerobes spp.

52
Q

Name 3 carbapenems.

A
  1. Imipenem,
  2. meropenem,
  3. ertapenem
53
Q

Carbapenems are resistant to?

54
Q

Imipenem is combined with __________, which works by __________.

A

Cilastatin

inhibiting dehydropeptidase 1 (DHP1) found in the brush border of the proximal renal tubule. (DHP1 is necessary for the hydrolysis of imipenem. It is not a beta lactamase inhibitor.)

55
Q

Which carbapenem has good CSF penetration?

56
Q

Which of the following carbapenems is not effective against Pseudomonas aeruginosa (&enterococcus)?

57
Q

How are carbapenems administered?

A

Parenterally (as poor absorption)

58
Q

If pt is allergic (anaphylaxis) to penicillin, what drugs can you not give her?//

Which drug classes of beta lactams have cross reactivity with penicillins?

A

Cephalosporins, carbapenems (cross hypersensitivity)

59
Q

Which drug class does aztreonam belong to?

A

Monobactam

60
Q

Aztreonam is effective against Gram-

A

negative bacteria (no activity against Gram positive and anaerobic microbes)

61
Q

Does aztreonam have cross-sensitivity to penicillin?

62
Q

How is aztreonam administered?

A

Parenterally IM/IV

63
Q

Which drug class does vancomycin belong to?

A

Glycopeptide- bact cell wall inhibitor

64
Q

Vancomycin is useful against Gram ___________

65
Q

How is vancomycin commonly administered?

A

Intravenously

66
Q

When is oral vancomycin preferred?

A

Clostridium difficile-associated diarrhea (CDAD)

or the more severe antibiotic-associated pseudo-membranous colitis (AAPMC).

67
Q

What is the first line of antibiotics for CDAD?

A

Vancomycin

68
Q

Vancomycin interferes with cell wall synthesis by inhibiting ___________

A

transglycosylation

b/n Ala-Ala of NAM & NAG

69
Q

Name 3 antibiotics that work by inhibiting bacterial cell wall synthesis, and are effective against MRSA?

A
  1. ceftobiprole (Fifth generation cephalosporins)
  2. ceftaroline (Fifth generation cephalosporins)
  3. Vancomycin
70
Q

How is vancomycin cleared?

A

Renal clearance

71
Q

Name 3 adverse effects related to vancomycin

A
  1. Nephrotoxicity,
  2. Ototoxicity,
  3. Red man syndrome (rash above nipple line due to histamine release w rapid infusion)
  4. rare thrombph
72
Q

How to resolve red man syndrome?

A
  1. Antihistamine

2. Prolong infusion vancomycin to 1-2 hrs

73
Q

Vancomycin resistance due to?

A

substituting terminal D-alanine for D-lactate/serine reducing vancomycin binding affinity –> VREnterococcus

74
Q

Vancomycin ineffective against?

A

all Gram -ve & mycobacteria

Antimicrobials (11 decks)

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