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Antibiotics > Cephalosporins Gen 5 > Flashcards

Cephalosporins Gen 5 Flashcards

1
Q

Which 5th gen cephalosporin is only available in Canada?

A

ceftobiprole

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2
Q

Which two types of infections are typically used to test safety/efficacy in new drug trials?

A

upper respiratory infections, skin/skin structure infections

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3
Q

Why are 5th generation cephalosporins active against MRSA?

A

structurally engineered to bind to PBP2a of MRSA

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4
Q

Besides MRSA, what other organisms are 5th generation cephalosporins active against that none of the 1-4 gen cephalosporins are?

A

enterococci

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5
Q

The gram-negative activity of 5th generation cephalosporins is similar to what 3rd generation cephalosporin?

A

ceftriaxone

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6
Q

What is the 5th generation cephalosporin available in the US?

A

ceftaroline fosamil (teflaro)

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7
Q

When was ceftaroline approved?

A

2010

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8
Q

Ceftaroline is FDA approved to treat what?

A

complicated skin/soft tissue infections (MRSA), community-acquired pneumonia

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9
Q

What organisms does ceftaroline have good activity against?

A

MSSA, MRSA, streptococci, enteric GNRs

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10
Q

What organisms does ceftaroline have moderate activity against?

A

acinetobacter, enterococcus faecalis

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11
Q

What organisms does ceftaroline have poor activity against?

A

pseudomonas aeruginosa, enterococcus faecium, anaerobes

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12
Q

When is PBP2a formed in staphylococci?

A

when the “mecA” gene is expressed in the chromosome

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13
Q

What are the four molecular beta lactamase classes based on protein sequence?

A

A, B, C, D

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14
Q

Which molecular beta lactamase classes based on protein sequence hydrolyze substrate by forming an acyl enzyme through an active serine site?

A

classes A, C, D

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15
Q

How does molecular beta lactamase class B (based on protein sequence) hydrolyze substrate?

A

hydrolyze metalloenzymes that utilize zinc (ion)

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16
Q

What is the problem with classifying beta lactamases based on protein sequence (even though it is non-controversial)?

A

not helpful from a clinical perspective

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17
Q

What is the other way to classify beta lactamases besides protein sequence?

A

according to ability to hydrolyze different classes of beta-lactams

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18
Q

What is the advantage of classifying beta lactamases based on what drugs they hydrolyze (even though it is controversial)?

A

it is clinically useful

19
Q

What are five types of beta-lactamases?

A

penicillinases (s. aureus), cephalosporinases, broad spectrum, extended spectrum beta lactamases, carbapenemases

20
Q

What does the KPC-2 enzyme stand for and why is it problematic?

A

Klebsiella pneumoniae carbapenemase 2; problem because there is nothing today that is effective against organism with this enzyme

21
Q

Group 1, Class C beta lactamases generally affect…

A

cephalosporins

22
Q

Group 2a, Class A beta lactamases generally affect ________ and contain what organism?

A

penicillins and Staphylococcus aureus

23
Q

Group 2be, Class A beta lactamases generally affect…

A

extended-spectrum beta lactams (3rd gen cephalosporins), monobactams

24
Q

Group 2f, Class A, and Group 3a, Class B beta lactamases affect…

A

carbapenems

25
Q

In which group/class is the KPC-2 enzyme found?

A

Group 2f, Class A

26
Q

Group 2b, Class A beta lactamases generally affect…

A

broad spectrum beta lactams

27
Q

Group 2br, Class A beta lactamases affect…

A

penicillins

28
Q

Group 2e, Class A beta lactamases affect…

A

extended-spectrum beta lactams (3rd gen cephalosporins)

29
Q

Which organisms usually naturally produce AmpC enzymes (think SPACE)?

A

serratia, pseudomonas, acinetobacter, citrobacter, enterobacter

30
Q

What is the purpose of the AmpC gene?

A

repressor gene that keeps beta-lactamase production in check (stops it or keeps it low when antibiotic not present)

31
Q

What is de-repression?

A

when the AmpC gene turns off when antibiotic present (so beta lactamase made) and turns back on when antibiotic not present

32
Q

What is stable de-repression?

A

when the AmpC gene doesn’t turn back on when the antibiotic not present (beta lactamase production remains high)

33
Q

What was a likely reason the MICs for SPACE organisms (that made AmpC) continued to go up despite ongoing treatment?

A

de-repression, or stable de-repression (worse)

34
Q

Extened-spectrum beta-lactamases mediate resistance to beta lactams that contain what?

A

oxyimino side chains (3rd gen ceph, oxyimino-monobactams)

35
Q

Extended-spectrum beta lactamses do not affect which beta lactams?

A

cefamycins (cefoxitin, cefotetan), carbapenems

36
Q

If an extended-spectrum beta lactamase is confirmed present, which beta lactams should automatically be reported as resistant?

A

penicillins, cephalosporins, aztreonam

37
Q

What are six known extended-spectrum beta lactamase producing organisms?

A

Klebsiella pneumoniae, klebsiella oxytoca, escherichia coli, pseudomonas aeruginosa, salmonella, proteus mirabilis

38
Q

Why are cefamycins not a good choice for treating extended-spectrum beta lactamase infections (even though ESBLs don’t affect them?

A

they are intrinsically not very active against many ESBL-producing organisms

39
Q

What should be avoided in order to minimize the development of ESBL-producing organisms?

A

using extended spectrum cephalosporins (3rd gen) for empiric treatment

40
Q

What are three empiric therapy options besides extended-spectrum cephalosporins that don’t facilitate the development of ESBL-producing organisms?

A

extended-spectrum penicillins, pencillins plus beta lactamase inhibitors, cefepime (4th gen ceph)

41
Q

Chromosomal-mediated AmpC beta lactamases confer resistance to what?

A

cefamycins

42
Q

Group 2b, Class A beta lactamases (affect broad-spectrum beta lactams) have what three enzymes?

A

TEM-1, TEM-2, SHV-1

43
Q

Are Group 1, Class C, Group 2br, Class A, and Group 3a, Class B beta lactamases inhibited by clavulanic acid?

A

no

44
Q

What beta lactamase group contains AmpC enzymes?

A

Group 1, class C

Antibiotics (13 decks)

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