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Disease & Defense > LEC 36 Antimicrobials IV > Flashcards

LEC 36 Antimicrobials IV Flashcards

1
Q

What is the DOC for MRSA?

A

Vancomycin

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2
Q

What clinical resistance is associated with vancomycin?

A
  • Enterococcal Resistance (VRE)
  • Enterococus faecium

However: Enterococcus faecalis is 100% suseptible to Vancomycin

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3
Q

What are the pharmacokinetics of vancomycin?

A
  • No absorption from GI tract - IV only
  • t1/2 = 6 hrs
  • Penetrates CSF when meninges inflamed
  • Eliminated by kidney (glomerular)
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4
Q

What are the adverse effects associated with vancomycin?

A
  • Hypersensitivities
  • Rapid IV injection - “vancomycin infusion reaction” - tx with benadryl and slow the infusion
  • Nephrotoxicity - less than aminoglycosides
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5
Q

What are the pharmacokinetics of beta lactams?

A
  • Food adsorbs penicillins - decreases F
  • Poor penetration into CSF (unless meninges inflamed) and prostate
  • Little to no liver metabolism - some ceph’s do liver metab and biliary excretion
  • Kidney elimination - t1/2 = 30-90 mins - Probenecid can compete and extend half life of drug
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6
Q

Which penicillinase-resistant penicillins are the DOC for susceptible strains of Staph aureus?

A

Nafcillin (IV/IM) or Oxacillin (oral)

“think staph… think naf”

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7
Q

What are the adverse effects of penicillins?

A
  • Hypersensitivities - rash (mild or severe - Stevens-Johnson syndrome), fever, serum sickness, anaphylaxis
  • Impaired platelet function (rare)
  • CNS toxicity - seizures if not dosed for CrCl
  • Alterations in normal microflora
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8
Q

How do beta lactams cause hypersensitivity rxns?

A
  • Beta-lactam rings bind amino groups on proteins
  • Antibodies recognize this compound as a hapten-protein complex and creates an immune response to the drug

Essentially creates a hapten-protein complex vaccine

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9
Q

What is different about cephalosporin metabolism compared to penicillins?

A
  • Many cephalosporins have longer half lives than penicillins
  • Some cephalosporins are metabolized by the liver by deacetylation
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10
Q

What is the spectrum of coverage of first gen cephalosporins?

A
  • Gram Positive cocci (Strep & Staph, but not MRSA or MRSE)
  • Gram Negative organisms: Proteus, E. coli, Klebsiella pneumoniae

Mnemonic: SS PEcK

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11
Q

Cephalexin is what generation cephalosporin?

A

First Generation

Given PO; Cefadroxil has better oral absorption and BID dosing

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12
Q

What is the spectrum of activity of the second generation cephalosporins?

A
  • Reduced gram positive compared to first gen
  • Increased gram neg compared to first gen: H. influenzae, Enterobacteriaceae, Neisseria (gonorrhoeae, meningitidis), P. mirabilis, E. coli, K. pneumoniae, Serratia

Mnemonic: HENPEcKS

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13
Q

Which two second generation cephalosporin drugs are effective against anaerobes?

A

Cefoxitin and Cefotetan

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14
Q

What is the spectrum of activity of third gen cephalosporins?

A
  • reduced gram positive
  • Increased gram neg:
  • H. influenzae
  • Enterobacteriaceae
  • Neisseria
  • P. mirabilis
  • E. coli
  • K. pneumoniae
  • M. catarrhalis
  • Better activity against Enterobacter

Mnemonic: HENPEcK ME

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15
Q

What is the DOC for Neisseria (gonorrheae, meningitidis) infxn?

A

Ceftriaxone

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16
Q

Which two 3rd gen cephalosporins are active against P. aeruginosa?

A

Cefoperazone and Ceftazidime

17
Q

What are the adverse effects of cephalosporins?

A
  • Hypersensitivities
  • some nephrotoxicity
18
Q

What is the spectrum of activity of fluoroquinilones?

A
  • more potent against gram neg
  • more active against gram pos
  • more active against intracellular organisms
  • poor activity against anaerobes (not for pus)
19
Q

What are the pharmacokinetics of fluoroquinilones?

A
  • Most are well absorbed orally - good for IV to PO switch
  • Chelators of divalent cations (Ca or Mg) - decrease absorption
  • Widely distributed in body
  • Elimination varies by drug
20
Q

What are the adverse effects of fluoroquinolones?

A
  • GI upset - N/V, abdominal discomfort
  • Hypo/Hyperglycemia
  • Photosensitivity
  • CNS: GABA inhibition, HA, dizziness, insomnia
  • Connective tissue - tendon rupture; do not use in kids & pregnant women
21
Q

Which two fluoroquinolones are the “respiratory quinolones”?

A

Moxifloxacin and Levofloxacin

22
Q

Ciprofloxacin is used to treat what?

A

Anthrax

2nd gen fluoroquinolone

23
Q

Aminoglycosides target what kind of bacteria?

A

Gram negative

24
Q

What is the DOC for VRE?

Vancomycin resistant enterococcus

A

Aminoglycoside + Beta-lactam

They are synergistic

25
Q

Describe the synergistic relationship of aminoglycosides and beta lactams when treating Enterococcus.

A
  • The beta lactam helps break down the cell wall
  • This helps the aminoglycoside penetrate the cell to reach its target (30S)
26
Q

What are the pharmacokinetics of aminoglycosides?

A
  • Renal elimination - t1/2 = 2-3 hours
  • t1/2 from tissues (renal & inner ear) = 30-700hrs
  • half life longer in pts with little or no renal function
  • At high concentrations - can disrupt cell membrane and can inhibit mitochondria
27
Q

What toxicities are associated with aminoglycosides?

A
  • Cochlear and Vestibular (Ototoxicity)
  • Nephrotoxicity

Hearing loss and vertigo type stuff

28
Q

Which aminoglycoside has the highest risk of nephrotoxicity?

A

Neomycin

29
Q

Which aminoglycoside has the lowest risk of nephrotoxicity?

A

Streptomycin

30
Q

Tetracyclines are the drug of choice for which infections?

A
  • Rickettsiae (Rocky Mt. Spotted Fever)
  • Chamydiae
  • Borrelia (Lyme)
  • Mycoplasma pneumoniae

useful against: H. pylori, Propionibacterium acnes, Treponema (syphilis)

31
Q

What are the adverse effects of tetracyclines?

A
  • GI - irritation/diarrhea; superinfection (pseudomembranous colitis)
  • Photosensitivity
32
Q

What are the adverse effects of macrolides?

A
  • GI - “gastric prokinetic activity”
  • Cholestatic jaundice
  • Cardio - prolonged QTc interval
33
Q

Which drug is commonly given to children to treat constipation?

A

Erythromycin

34
Q

Which two drug classes cause prolonged QTc intervals?

A
  • Macrolides
  • Fluoroquinolones

Disease & Defense (37 decks)

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