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Anti-microbes > Beta Lactams > Flashcards

Beta Lactams Flashcards

1
Q

What is the mechanism of action of the beta lactams?

A

They interfere with the synthesis of the bacterial cell wall peptidoglycan by binding to the active site of the trans-peptidase enzyme (PBP), preventing the cross-linking of terminal peptide components of the linear polymer chains.

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2
Q

What type of antibiotics are beta lactams?

A

Bactericidal

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3
Q

What are the 4 classes of beta lactams?

A
  1. Penicillins
  2. Cephalosporins
  3. Carbapenems
  4. Monobactam
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4
Q

What are the 4 classes of penicillins?

A
  1. Natural penicillins
  2. Penicillinase-resistant penicillins
  3. Aminopenicillins
  4. Anti-pseudomonal penicillins
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5
Q

What is the coverage for natural penicillins?

A
  1. Mostly gram-positive
  2. Some gram-negative microbes and spirochetes (syphilis)
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6
Q

What are the 2 natural penicillins?

A
  1. Penicillin G - IM, IV
  2. Penicillin V - PO
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7
Q

How are natural penicillins excreted?

A

Renal clearance

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8
Q

What is the coverage of penicillinase-resistant penicillins?

A
  1. Penicillinase-producing Staphylococci & other gram-positives

Ineffective against gram-negative organisms

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9
Q

How is penicillinase-resistant penicillin excreted?

A

Renal clearance

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10
Q

How is penicillinase-resistant penicillin CSF penetration?

A

Nil

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11
Q

What is the route of administration of penicillinase-resistant penicillins?

A

PO, IM, IV

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12
Q

What is the CSF penetration of natural penicillins?

A

Only IV aqueous penicillin G reaches effective conc.

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13
Q

How are beta-lactamase-resistant penicillins resistant to beta-lactamases?

A

They possess bulky side groups which limit the beta-lactamase accessibility to the catalytic site of action

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14
Q

What is the coverage for aminopenicillins?

A
  1. Broad spectrum for both gram-positives & gram-negatives
  2. Does not cover pseudomonas or Klebsiella
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15
Q

How are aminopenicillins able to exhibit activity against gram-negatives?

A

They possess additional hydrophilic groups, allowing their penetration into gram-negative bacteria via the porins

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16
Q

What is the CSF penetration for aminopenicillins?

A

IV ampicillin & IV amoxicillin can reach adequate CNS conc.

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17
Q

How are aminopenicillins excreted?

A

Renal clearance

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18
Q

What is the coverage for anti-pseudomonal penicillins?

A
  1. Greater activity against gram-negatives; especially Pseudomonas, Proteus & Klebsiella
  2. Also covers gram-positives
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19
Q

What is the CSF penetration for anti-pseudomonal penicillins?

A

Fairly high penetration

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20
Q

What is the main anti-pseudomonal penicillin used?

A

IV Piperacillin + Tazobactam

21
Q

How are anti-pseudomonal penicillins excreted?

A

Primary renal clearance

22
Q

What is the mechanism of action of beta-lactamase inhibitors?

A

Beta-lactamase inhibitors have a strong affinity for beta lactamases, allowing them to bind and inactivate it

23
Q

What are the 4 mechanisms of resistance to penicillin?

A
  1. Altered PBP to have reduced affinity for penicillins
  2. Production of beta-lactamases
  3. Decreased porin production which causes the antibiotic to be unable to reach the PBP
  4. Presence of efflux pumps
24
Q

What are the 3 adverse reactions to penicillins?

A
  1. Allergy
  2. GI symptoms - Nausea/vomiting
  3. Neurotoxicity
25
Q

Going down the generations of cephalosporins, what increases?

A
  1. Increased coverage against gram-negatives
  2. Increased resistance to beta lactamases
  3. Increased penetration into the CSF from 3rd-gen
26
Q

How are cephalosporins eliminated?

A

Most are through renal clearance

Only ceftriaxone is cleared hepatically

27
Q

What are the 2 adverse reactions from taking cephalosporins?

A
  1. Hypersensitivity - 1% cross allergy between cephalosporins & penicillins
  2. GI symptoms
28
Q

What are the bacteria that are resistant to cephalosporins?

A

LAME

Listeria, Atypicals, MRSA (5th-gen ceftaroline effective & Enterococcus spp.

29
Q

What is the coverage of first-gen cephalosporins?

A

Mainly Streptococci & S. aureus

30
Q

Which cephalosporins cover P. aeruginosa?

A
  1. Ceftazidime
  2. Cefepime
31
Q

What is the spectrum of coverage for ceftriaxone?

A
  1. Gram-positives: Streptococci & S. aureus
  2. Enterobacterales, N. meningitidis, N. gonorrhoeae & H. influenzae
32
Q

What is the spectrum of coverage of Ceftazidime?

A

Same as ceftriaxone but with Pseudomonas & B. pseudomallei coverage

33
Q

What is the spectrum of coverage of Cefepime?

A

Same as third-gen but with pseudomonas coverage

34
Q

What cephalosporin covers MRSA?

A

Ceftaroline

35
Q

What is the spectrum of coverage of second-gen cephalosporins?

A

Used in CAP

Activity against E. coli, Klebsiella, Proteus & H. influenzae

36
Q

What type of bacteria are carbapenems used against?

A

ESBL producing bacteria

37
Q

What are the 3 carbapenems?

A
  1. Imipenem
  2. Meropenem
  3. Ertapenem
38
Q

Which carbapenem has good CSF penetration?

A

Meropenem

39
Q

What is the route of administration of the carbapenems?

A

IV

40
Q

Which carbapenem is slightly nephrotoxic?

A

Imipenem

41
Q

What is the spectrum of coverage of the carbapenems?

A
  1. Broad spectrum coverage against gram-negatives & positives
  2. Ertapenem does not cover P. aeruginosa & Enterococcus spp.
42
Q

Do carbapenems have activity against MRSA?

A

No

43
Q

What are the 3 adverse reactions to carbapenems?

A
  1. Hypersensitivity - might have slight cross allergy between carbapenems & penicillins
  2. GI symptoms
  3. Neurotoxicity
44
Q

What is the spectrum of coverage for aztreonam?

A

Only gram-negative bacteria

45
Q

What is the route of administration of aztreonam?

A

IM/IV

46
Q

What is the CSF penetration for aztreonam?

A

Penetrates CSF if meninges inflammed

47
Q

How is aztreonam excreted?

A

Renal clearance

48
Q

What are the adverse effects of aztreonam?

A

Skin rash

49
Q

What are the 7 cephalosporins and which generation do they belong to?

A

1st Gen - Cefazolin & Cephalexin
2nd Gen - Cefuroxime
3rd Gen - Ceftriaxone & Ceftazidime
4th Gen - Cefepime
5th Gen - Ceftaroline

Anti-microbes (9 decks)

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