Drugs for Skin/Soft tissue Infections Flashcards

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1
Q

Uncomplicated skin and soft tissue infections in immunocompetent persons are most commonly caused by?

A

Staph aureus and Strep pyogenes

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2
Q

Complicated skin infections (e.g. with burns, diabetes, ulcers, etc) are more likely be caused by what?

A

more commonly polymicrobial and often include anaeobes and gram neg rods, such as E. coli and Pseudomonas

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3
Q

What are the drug options for uncomplicated non-MRSA infections?

A

these are typically susceptible to beta-lactamase resistance penicillins (dicloxacillin, nafcillin, and oxacillin) and 1st-gen cephalosporins (cephalexin, cefazolin)

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4
Q

What if a patient with uncomplicated non-MRSA infections has an allergy to a penicillin or cephalosporins?

A

Clindamycin (50s inhibitor) or Vanco can be used

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5
Q

What is the typical allergy to penicillins?

A

this is typically an IgE-mediated allergy (histamine release causing urticaria, angioedema, anaphylaxis). Remember that historically, patients who are truly allergic to a penicillin would also display symptoms to a 1st or 2nd gene cephalosporin (due to related R1 side chain rather than beta-lactam structure)

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6
Q

Again, it is hypothesized that the R1 side chain of both penicillins and cephalosporins is responsible for cross-reactive hypersensitivity. Which drugs possess this adduct?

A
  • penicillin G, ampicillin, amoxicillin
  • cefoxitin, cefaclor, cephalexin, cefadroxil, cefprozil
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7
Q

Most penicillins are eliminated renally and require dose-adjustment in renal failure, except which drugs?

A

nafcillin (mostly hepatic and only requires dose adjustment if hepatic AND renal involvment present)

  • Oxacillin (hepatic elimination)
  • Dicloxacillin (renal elim but no adjustment needed)
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8
Q

Does clindamycin require dose adjustment in RF? Vanco? What about cephalosporins

A

While vanco and cephalosporins DO require dose adjustment in RF, clindamycin is eliminated hepatically and does not

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9
Q

What is a common AE for beta-lactams?

A

Hypersensitivity and GI distress

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10
Q

What is another common AE for penicillinase-resistant penicillins (like nafcillin, dicloxacillin, and oxacillin)

A

interstitial nephritis

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11
Q

AEs of vanco?

A

Red man syndrome and hypotension with rapid IV injection

Nephro (reversible) and ototoxicity

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12
Q

What are some illnesses associated with CA-MRSA?

A

cellulitis, abscesses, necrotizinf fasciitis, and sepsis rarely

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13
Q

How would simple CA-MRSA induced abscesses and less serious skin and soft tissue infections be treated?

A
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14
Q

What drug class SHOULD NOT be used empirically to treat MRSA? Why?

A

Fluoroquinolones due to increasing resistance

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15
Q

How does Linezolid work?

A

Binds to the 23S of the 50S subunit and prevents initiation complex formation with the 70S subunit

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16
Q

What are the AEs of Bactrim?

A

N/V, dyspepsia

photosensitivity

Fetal risk in 1st and 3rd trimester

17
Q

How is Bactrim eliminated?

A

Renal (dose-adjustment needed)

18
Q

How are the tetracyclines eliminated?

A

Hepatic and renal (dose adjustment required in RF)

19
Q

AEs of tetracyclines?

A
  • hepatotoxicity
  • discolored teeth
  • fetal risk
  • photosensitivity
20
Q

How is clindmaycin eliminated?

A

Hepatic (no dose adjustment in LF/RF)

21
Q

AEs of Clinda?

A

C-difficile infection

  • SJS
  • jaundice
22
Q

AEs of Linezolid?

A
  • optic neuropathy and vision loss
  • serotonin syndrome and seizures
  • myelosuppression
  • lactic acidosis
23
Q

What causes optic neuropathy with linezolid?

A

thought to be casued by mitochondrial dysfunction in the optic nerve (reversible upon discontinuing the drug)

24
Q

What is serotonin syndrome?

A

mental status changes and autonomic hyperactivity caused by excessive levels of serotonin (that is a common effect of co-administration of serotonin increasing drugs such as isoniazid, linezolid, and SSRIs for depression)

25
Q

How should patients with complicated MRSA skin and soft tissue infections be treated?

A

they should be hospitalized and given IV vanco (or linezolid/dapto if toxin production is an issue)

26
Q

How should complicated polymicrobial infections be treated?

A

add a MRSA drug to a broad spectrum penicillin (piper/tazo) or imi/cilastatin OR give a 5th generation cephalosporin called CEFTAROLINE (if co-infection with P. aeruginosa or anaerboes is not suspected)

27
Q

Metabolism of Ceftaroline?

A

IV drug that is predominantly renally eliminated (dose adjustment in RF)

28
Q

AEs of Ceftaroline?

A

GI disturbance

hypokalemia and phlebitis

C. difficile, ALT/AST elevation, and hemolytic anemia rarely reported

29
Q

How does Dapto work?

A

IV drug that binds to and depolarizes the abcterial membrane, inhibiting DNA/RNA?protein synthesis

30
Q

AEs of Dapto?

A

rhabdomyolysis (monitor serum creatine kinase levels)

31
Q

AEs of piperacillin/tazo?

A

-myelosuppression

Gi disturbance

32
Q

AEs of carbapenems?

A

seizures at high doses

33
Q

T or F. Dapto, Piperacillin, and carbapenems should be dose-adjusted in RF

A

T.