Bacterial cell wall synthesis inhibitors Flashcards

Recall some of the key information covered in this topic on bacterial cell wall synthesis inhibitors

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 side of which enzyme?

A

Transpeptidase (penicillin binding protein)

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3
Q

Name 4 types of beta lactams

A

Penicillins, cephalosporins, carbapenems, monobactam

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4
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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5
Q

Which natural penicillin is administered parenterally?

A

Penicillin G

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6
Q

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

A

Penicillin G

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7
Q

Are natural penicillins commonly used against Staphylococcus aureus?

A

No

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8
Q

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

A

Penicillinase resistant penicillins

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9
Q

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

A

They produce penicillinases

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10
Q

Which bacteria is cloxacillin effective against?

A

Methicillin Sensitive Staphylococcus aureus (MSSA)

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11
Q

How are the penicillins mainly cleared?

A

Renal clearance

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12
Q

Name the 2 aminopenicillins

A

Ampicillin, amoxicillin

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13
Q

Are aminopenicillins effective against beta lactamase producing strains of bacteria?

A

No

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14
Q

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

A

Amoxicillin

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15
Q

Does aminopenicillins sufficiently cover Pseudomonas and Klebsiella?

A

No

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16
Q

How are aminopenicillins cleared?

A

Renal excretion

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17
Q

How is piperacillin administered?

A

Intravenously

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18
Q

Which class of penicillins has coverage against Pseudomonas, Proteus and Klebsiella?

A

Anti-pseudomonal penicillins (piperacillin)

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19
Q

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

A
  1. Augmentin (Amoxicillin + clavulanic acid)
  2. Unasyn (ampicillin + sulbactam)
  3. Zosyn (piperacillin + tazobactam)
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20
Q

How do beta-lactamase inhibitors work?

A

They either covalently bind at or near the active site of the β-lactamase and restructures it, permanently inactivating. In doing so, they protects other beta-lactam antibiotics from beta-lactamase catalysis.

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21
Q

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

A

MRSA (methicillin resistant Staphylococcus aureus)

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22
Q

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

A
  1. Anaphylaxis
  2. Stevens Johnson syndrome
  3. Toxic epidermal necrolysis
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23
Q

Which generation of cephalosporins does cefazolin and cephalexin belong to?

A

First generation

24
Q

Which generation of cephalosporins are primarily administered orally?

A

First and second generation cehalosporins. Cefazolin (first generation) is an exception.

25
Q

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

A

Parenterally

26
Q

Name at least 3 types of microbes against which first and second generation cephalosporins are ineffective?

A
  1. Pseudomonas aeruginosa and

(LAME species)

  1. Listeria monocytogenes,
  2. Atypicals (Mycoplasma, Chlamydia, Legionella spp.),
  3. MRSA, and
  4. Enterococcus species
27
Q

Ceftriaxone belongs to which generation of cephalosporins?

A

Third generation

28
Q

Name one cephalosporin from the third and fourth generation each which is effective against Pseudomonas aeruginosa.

A

Third generation – Ceftazidime

Fourth generation - Cefepime

29
Q

Which generation of cephalosporins has coverage against MRSA?

A

Fifth generation (ceftaroline)

30
Q

How are most cephalosporins cleared?

A

Renal clearance

31
Q

How is ceftriaxone cleared?

A

Hepatic clearance

32
Q

Explain the mechanism of resistance underlying MRSA.

A

MRSA expresses an altered penicillin binding protein (PBP2a) with reduced affinity for the penicillins

33
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
34
Q

Does cephalosporin have cross reactivity with penicillins?

A

Yes

35
Q

Does cephalosporin have cross reactivity with penicillins?

A

Yes

36
Q

Name the class of antibiotics that are commonly used against extended spectrum beta-lactamase (ESBL) producing bacteria?

A

Carbapenems

37
Q

Name 3 carbapenems.

A
  1. Imipenem,
  2. meropenem,
  3. ertapenem
38
Q

How are carbapenems administered?

A

Parenterally

39
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.)

40
Q

Can carbapenems be used to treat MRSA?

A

No

41
Q

Which carbapenem has good CSF penetration?

A

Meropenem

42
Q

Which of the following carbapenems is not effective against Pseudomonas aeruginosa?

A

Ertapenem

43
Q

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

A

Cephalosporins, carbapenem

44
Q

Which drug class does aztreonam belong to?

A

Monobactam

45
Q

Aztreonam is effective against Gram-

A

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

46
Q

Does aztreonam have cross-sensitivity to penicillin?

A

No

47
Q

What are some adverse effects related to the use of penicillins, cephalosporins and carbapenems?

A

GIT related symptoms (vomiting diarrhea), hypersensitivity (Symptoms range in severity, from a minor rash to life-threatening conditions like anaphylaxis)

48
Q

Vancomycin is useful against Gram ____________

A

positives

49
Q

How is vancomycin commonly administered?

A

Intravenously

50
Q

When is oral vancomycin preferred?

A

Clostridium difficile-associated diarrhea (CDAD) or the more severe antibiotic-associated pseudo-membranous colitis.

51
Q

What is the first line of antibiotics for CDAD?

A

Vancomycin

52
Q

Vancomycin interferes with cell wall synthesis by inhibiting __________

A

transglycosylation

53
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
54
Q

How is vancomycin cleared?

A

Renal clearance

55
Q

Name 3 adverse effects related to vancomycin

A
  1. Nephrotoxicity,
  2. Ototoxicity,
  3. Red man syndrome
56
Q

Which beta-lactam has coverage against MRSA?

A

5th generation cephalosporin like Ceftaroline