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(C) CM 1B: ID/EENT > Lecture 2: Antibiotics Part I > Flashcards

Lecture 2: Antibiotics Part I Flashcards

1
Q

How do beta-lactams work relative to bacterial physiology?

A

They latch onto transpeptidase enzymes, preventing the layers of peptidoglycan from sticking together.

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2
Q

What ABX fall under beta-lactams?

A

PCNs
Cephalosporins
Carbapenems
Monobactams

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3
Q

What does a beta-lactam ring look like?

A

3 carbon 1 nitrogen square with a double bond to an O.

See slide 8 for visual.

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4
Q

What is the MOA of a beta-lactam?

A
  1. Drug binds to pencillin-binding proteins (PBP)
  2. This inhibits bacterial peptidoglycan synthesis, preventing bacterial replication. (Bacteriostatic)
  3. Binding to PBP activates bacterial autolytic enzymes that cause cell wall lysis. (Bactericidal)
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5
Q

How do G+ bacteria fight back against beta-lactams?

A
  1. Reduced binding affinity to PBPs.
  2. Productions of beta-lactamases to cleave the abx.
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6
Q

How do G- bacteria fight back against beta-lactams?

A
  1. Loss of outer membrane proteins.
  2. Beta-lactamases in periplasmic space.
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7
Q

What does penicillin become if the beta-lactam ring is broken?

A

Penicilloic acid

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8
Q

What is ABX resistance classified as?

A

Public Health Crisis!!!

2 millions infections
23,000 deaths

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9
Q

What are natural penicillins first-line for?

A

Group A Strep Throat
Syphilis (Treponema pallidum) (Spirochetes)

N. meningiditis (sometimes)

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10
Q

What are some pros and cons of natural pcns?

A

Cons:
Susceptible to beta-lactamase
Tastes bad
Multiple doses required
Increasing resistance

Pros:
Cheap
Safe

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11
Q

What are antistaphylococcal PCNs indicated for as first-line?

A

SSTIs with S. aureus and staph epidermis

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12
Q

What are the antistaphylococcal PCNs?

A

Dicloxacillin
Nafcillin
Oxacillin

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13
Q

What is the purpose of methicillin?

A

Identifying microbial resistance.

DO NOT USE FOR TX.

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14
Q

What are aminopenicillins first-line treatment for?

A

Otitis Media:
H. influenzae
S. pneumoniae
Moraxella Catarrhalis (M. Cat)

Prophylaxis for endocarditis!

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15
Q

Which aminopenicillin is better for PO?

A

Amoxicillin. (also tastes like bubblegum so children will take it)

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16
Q

What is the main difference in coverage between natural PCNs and the aminoPCNs?

A

Increased G- coverage.

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17
Q

What are the advantages of AminoPCNs over natural PCNs?

A

Higher oral absorption and longer half-life = less frequent dosing.

Better G- coverage.

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18
Q

What are the PCN/Beta-lactamase inhibitor combos first-line for?

A

Augmentin is firstline for sinusitis, pneumonia/COPD exacerbations.

This includes S. pneumo, H. flu, and S. aureus.

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19
Q

How long should someone be on abx for a sinus infection?

A

At least 10 days, because sinus infections take longer to treat.

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20
Q

What are the considerations when RXing a PCN/Beta-lactamase inhibitor?

A

Increased Cost
Increase GI SE
Reserved for more severe infections.

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21
Q

What is pip/tazo indicated for?

A

Severe polymicrobial infections:
Genital or urinary tract
Peritonitis/ruptured viscus
SSTI
Lower respiratory tract
Septicemia

Pseudomonas
Proteus

22
Q

What is cephalexin (Keflex) and what is it indicated for?

A

1st gen cephalosporin.

Indicated for G+ staph and strep:
Minor skin infections
Impetigo
Pharyngitis/OM (except H. flu)

G-:
E. coli in simple cystitis, esp. in pregnancy. (alt to metro)

Very affordable with QID dosing.

23
Q

What is cefazolin (Ancef) indicated for?

A

1st gen cephalosporin.

IV/IM only.

Indicated for surgical prophylaxis (clean)
Serious MSSA infections like endocarditis, pneumonia, and UTI

Note:
Dr. G commonly uses ancef as the ortho’s go to ABX.

24
Q

What is cefadroxil (Duricef, Ultracef) indicated for?

A

Pharyngitis/tonsillitis

PO only but longer half-life than cephalexin, has BID dosing.

25
Q

Which 1st gen cephalosporin cannot be taken PO?

A

Ancef/Cefazolin

26
Q

What are cefoxitin/cefotetan indicated for?

A

Prophylaxis in dirty surgeries (vaginal/colorectal)

IV only, but better G- coverage.

2nd gen cephalosporin.

27
Q

What are cefuroxime/cefaclor/cefprozil indicated for?

A

2nd line for:
Pharyngitis
Sinusitis
OM
Upper & lower respiratory tract infections

PO only, 2nd gen cephalosporins.

28
Q

What is ceftriaxone/Rocephin indicated for?

A

First line for N. gonorrheae.
Good pneumococcal coverage. (used with a macrolide)

Surgical prophylaxis for abdominal.
Meningitis
PID

IM/IV only.

3rd gen cephalosporin.

29
Q

What are cefdinir(omnicef)/cefixime(suprax) indicated for?

A

Second line for upper and lower respiratory tract infections.
SSTIs

Oral only.

3rd gen cephalosporin.

Note:
First-line is aminoPCNs.

Has a lower dosing than keflex for SSTIs.

30
Q

What is cefepime(maxipime) indicated for?

A

Severe infections
Meningitis
Anti-pseudomonal

IV/IM only

Only 4th gen cephalosporin.

31
Q

What is ceftaroline(teflaro) indicated for?

A

VRE
MRSA

IV only.

5th? gen cephalosporin.

32
Q

Which cephalosporin gen has the worst G+ coverage?

A

3rd gen.

33
Q

Which cephalosporin gen has the worst G- coverage?

A

1st gen.

34
Q

Which cephalosporin gen begins penetrating the CNS?

A

3rd gen.

35
Q

What are monobactams indicated for?

A

Severe infections of:
Urinary tract (E. coli)
Bacteremia/septicemia caused by G- only.
INHALATION: cystic fibrosis and respiratory infections.

36
Q

What is unique about a monobactam?

A

Inhalation route is possible.
NO coverage against G+ or anaerobes.
NO cross-reactivity with PCNs.

37
Q

What is the preferred alternative to monobactams?

A

3rd and 4th gen cephalosporins.

Better coverage with less SE.

38
Q

Why is cilastatin added to imipenem?

A

Prevents inactivation of imipenem in the renal tubules of the kidney.

39
Q

Which carbapenem does NOT cover pseudomonas?

A

Ertapenem (Invanz)

40
Q

What are carbapenems indicated for?

A

Urinary tract
Meningitis
Peritonitis/intra-abdominal infections
Resistant wounds (chronic diabetic wounds)
Osteomyelitis

IV/IM only.

41
Q

What beta-lactams are most likely to cause GI SE?

A

Augmentin
Higher gen cephalosporins

42
Q

What are the main SE of beta-lactam use?

A

N/V/D
Vaginal candidiasis

43
Q

What adverse events are associated with beta-lactam use?

A

Hypersensitivites
C. diff associated colitis
Drug induced nephritis
Hematologic abnormalities: Anemia/thrombocytopenia
CNS toxicity (high dose PCN, carbapenems)

44
Q

What kind of ABX are usually given to people who state they have a PCN allergy?

A

Broad spectrum

45
Q

How many people with actual type 1 hypersensitivity reactions to PCN lose their sensitivity?

A

80% in 10 years.

46
Q

How much of the US populations has an actual type 1 hypersensitivity to PCN?

A

<1%

47
Q

How are most beta-lactams metabolized/excreted?

A

Renal.

Minimal liver metabolism
Minimal CYP450 interaction

48
Q

In what beta-lactams is neutropenia a concern?

A

Antistaphylococcal PCNs
Carbapenems

If only > 10 days of parenteral therapy.

49
Q

What pregnancy category are beta-lactams?

A

B

50
Q

What can beta-lactams decrease the efficacy of?

A

OCPs

(C) CM 1B: ID/EENT (27 decks)

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