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Antibiotics > Penicillins > Flashcards

Penicillins Flashcards

1
Q

PCN MOA

A

Binds to transpeptidases (penicillin binding proteins)

Mimics alanine (d ala d ala) residues

Inactivates enzymes

Bacterial cell wall breakdown>wall creation —> autolysis

PCN BACTERICIDAL

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2
Q

Natural PCNs

A

PCN G- IV and IM
PCN VK- oral

Probenecid- gout drug, inhibits renal secretion of PCN, boosts PCN levels

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3
Q

Natural PCN resistance (3)

A
  1. Modified penicillin binding proteins
  2. Reduced bacterial cell penetration- GN poor penetration bc protected by outer membrane and bacteria can decrease number of porins
  3. Beta lactamase enzyme
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4
Q

Beta lactamase (penicillinase)

A

Bacterial enzymes

Degrade beta lactamase compounds
- PCN G and VK, other PCNs, cephalosporins

GN bacteria- found in PERIPLASM

STAPH AUREUS and GP- beta lactamase a secreted, produce more enzyme than GN

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5
Q

B lactamase inhibitors (4)- CAST

A

Clavulanic acid
Avibactam
Sulbactam
Tazobactam

Added to aminoPCNs and antistaphylococcal PCNs to expand coverage

No effect alone

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6
Q

PCN G and VK clinical use (3)

A

Narrow spectrum

  1. GP- GAS (strep throat) and actinomyces
  2. Treponema pallidum (syphillis)
  3. Only susceptible isolates- N meaning idiots and strep PNA
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7
Q

PCN AEs 4, same for cephalosporins and sulfonamides

A

Type 1- acute, IgE, anaphylaxis, urticaria, bronchospasm

Type 2- direct coombs + hemolytic anemia, IgE (PCN acts as happen, abs against PCN bound to RBCs)

Type 3- serum sickness (days to weeks after exposure, complement activation, IgG, fever, urticaria, LAD, arthritis)

Type 4- maculopapular rash (mc with aminoPCN and EBV pharyngitis), interstitial nephritis (PCN acts as hapten)- fever, oliguria, high BUN/Cr, eosinophils, WBC, WBC casts in urine

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8
Q

C diff infection

A

Diarrhea after abx
Abx depletes normal flora
C diff growth—> pseudomembranous colitis

Frequently caused by

  1. CLINDAMYCIN
  2. Fluoroquinolones
  3. Cephalosporins
  4. PCNs
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9
Q

Jarisch Herxheimer Reaction

A

Flu like syndrome (fever, malaise, HA, myalgia, flushing, chills) after PCN for spirochetes (classically: syphilis) d/t killed bacteria releasing toxins

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10
Q

Antistaphylococcal PCNs 3

A

Oxacillin
Nafcillin
Dicloxacillin

Methicillin was prototype

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11
Q

Antistaphylococcal PCN use

A

Remember staph and strep found on skin- Covers NON MRSA staph and most strept
Community acquired cellulitis
Impetigo- honey crusted lesions on skin in peds, caused by s aureus
Staph endocarditis

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12
Q

AminoPCN 2

A

Amoxicillin- oral
Ampicillin- IV

Penetrate porin channel of GN

Sensitive to beta lactamase enzymes

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13
Q

Aminopenicillin coverage 6

A 
H influenza
E. coli
Proteus
Salmonella
Shigella
Listeria (GP)

Used for:
Otitis media
Bacterial sinusitis
MENINGITIS- newborns, elderly, Listeria coverage

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14
Q

Aminopenicillins and maculopapular rash

A

MC with viral infection

Classic- EBV infection with sore throat, amoxicillin given for presumed bacterial pharyngitis, maculopapular rash

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15
Q

SJS and TEN common with which abx class?

A

AminoPCNs
Sulfonamides
Cephalosporins

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16
Q

Amoxicillin/clavulanic acid, ampicillin/sulbactam

A

Increases activity against S aureus, H influenza, and anaerobes (B FRAGILIS)

Used in-
Otitis media/sinusitis (Broad spectrum)
Bite wounds (polymicrobial with anaerobes)

17
Q

Antipseudomonal PCNs 2

A

Ticarcillin
Piperacillin

Greater porin penetration

Effective against P aeroginosa and more GN

Broad spectrum when used with b lactamase inhibitors
1. Most GP, GN (Psuedomonas) and anaerobes
NOT MRSA

Inpatients with GN sepsis/PNA

18
Q

Beta lactam abx 3

A

Carbapenems
Aztreonam
Cephalosporins

All bind transpeptidases, prevents peotidoglycan cross linking, bacterial cell autolysis, bactericidal

Susceptible to beta lactamase enzymes

19
Q

Carbapenems 4

A

Imipenem
Meropenem
Ertapenem
Doripenem

Most resistant to most beta lactamase enzymes

DRUG OF CHOICE FOR ESBL BACTERIA

Broad spectrum- GP, GN, Psuedomonas, Enterobacter, anaerobes, B fragilis

20
Q

Extended Spectrum Beta Lactamases

A

Plasmid mediated

Confer R to most beta lactam abx

Found in only GN:
Pseudomonas
Klebsiella
E. coli
Enterobacter
Salmonella
Serration
Shigella
21
Q

Imipenem

A

Metabolized by kidneys

MUST admin with CILASTATIN to inhibit PCT enzyme dihydropeptidase I to decrease renal tox

22
Q

Carbapenems AES

A

N/V/D
Skin rash
NEUROTOXICITY at high doses or renal failure - seizures dt inhibition of GABA RECEPTORS

lowest seizure risk with MEROPENEM

23
Q

Aztreonam (monobactam)

A

Binds PENICILLIN BINDING PROTEIN 3- prevents peptidoglycan cross linking

PBP3 only in GN

Aztreonam only active against GN (incl pseudomonas)

24
Q

Aztreonam use

A

IV only- inpatients

Synergistic with aminoglycosides

NO CROSS REACTIVITY IN PCN ALLERGIC PTS

Can use in PCN allergic patients

25
Q

1st gen cephalosporins 2 (+PeCK)

A

Cefazolin
Cephalexin

Cefazolin used pre op to prevent S aureus wound infection

GP
Proteus
E. coli
Klebsiella

26
Q

2nd gen cephalosporins 3 (HENS PeCK)

A

Cefuroxime
Cefoxitin
Cefotetan

Hib 
Enterobacter
Neisseria
Serratia
Proteus
E. coli
Klebsiella

B fragilis (anaerobe)

27
Q

Cefuroxime use

A 
Otitis media (S PNA, H flu)
UTI in peds (e coli, no fluoroquinolones in peds)
28
Q

Cefoxitin/cefotetan use

A

IV
PID- cover Neisseria, give with doxycycline for Chlamydia coverage

Pre op in peds with appendicitis- covers E. coli, GN, some anaerobes, usually given with metronidazole

29
Q

3rd gen cephalosporins 3

A

Ceftriaxone
Cefotaxime
Ceftazidime- covers pseudomonas

More resistance to beta lactamase enzymes

Good CSF penetration- meningitis

30
Q

Ceftriaxone

A

Used for N gonorrhea

Commonly used in meningitis

  • active against S PNA, N meningiditis
  • good CSF penetration
31
Q

Cefepime

A

4th gen cephalosporin

Hospital patients with serious GN infections

32
Q

Ceftaroline

A

5th gen cephalosporin

Active against MRSA and VRSA

Binds PBP2a- MRSA specific PBP

No Psuedomonas coverage

33
Q

Cephalosporin resistance mechanisms 3

A
  1. Modified PBPs
  2. Altered cell permeability
  3. Beta lactamase
34
Q

Cephalosporin AES 6

A 
HYPERSENSITIVITY RXN SIMILAR TO PCN:
Anaphylaxis
Maculopapular rash
Serum sickness- fever, rash, arthritis 
Hemolytic anemia- drug addiction hapten 
Interstitial nephritis 
SJS/TEN

Some cross reactivity with PCNs

35
Q

Vitamin K deficiency and abx

A

Gut bacteria produce vitamin k2
Necessary for proper clotting
Abx reduce bacterial vit k production—> increased INR and potential bleeding

Common problem for pts on WARFARIN

36
Q

Hypoprothrombinemia

A

Cefotetan and cefazolin inhibit epoxied reductse (same as warfarin)
Decreased liver synth of clotting factors
Can prolong PT/INR
Reversible with vitamin K
Mostly in malnourished pts

37
Q

Special cephalosporin AEs 3

A
  1. Nephrotoxic with aminoglycosides
  2. Hypoprothrombinemia
  3. Disulfiram reaction- EtOH with cephalosporins
    Warmth, flushing, sweating
    Inhibition of acetaldehyde dehydrogenase -> accumulation of acetaldehyde

Antibiotics (8 decks)

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