Lesson 11

Antibiotics Overview

  • Pseudomembranous Colitis: Most common side effect of prophylactic antibiotics.
  • Allergic Reactions: Commonly caused by beta-lactam antibiotics (penicillins and cephalosporins).
    • Low rate of cross-reactivity (<1%) between penicillins and cephalosporins.
    • Third- and fourth-generation cephalosporins have the lowest cross-reactivity rates.
  • Usage Guidelines:
    • Cephalosporins can be used if PCN allergy was not IgE mediated or did not cause exfoliative dermatitis.
    • Alternatives for severe allergic reactions: Vancomycin or clindamycin.
  • Administration of Vancomycin:
    • Administer at 10-15 mg/kg over 1 hour to reduce histamine release.
  • Contraindicated During Pregnancy:
    • Chloramphenicol, erythromycin, fluoroquinolones, tetracyclines.

Antibiotic Classes and Examples

  • Beta-Lactams: Penicillin, Cephalosporins, Ampicillin
  • Aminoglycosides: Gentamicin, Streptomycin
  • Tetracyclines: Doxycycline
  • Fluoroquinolones: Ciprofloxacin, Levofloxacin, Moxifloxacin
  • Macrolides: Erythromycin
  • Other: Clindamycin, Vancomycin, Metronidazole

RisksAssociated with Antibiotics

  • Common Risks: Allergic reactions, ototoxicity, nephrotoxicity, hepatotoxicity, muscle weakness, gastrointestinal intolerance.
  • Specific Reactions: Tendonitis and tendon rupture, histamine release (leading to hypotension or Red man syndrome), Stevens-Johnson syndrome, peripheral neuropathy, alcohol intolerance.

Key Facts about Antibiotics

  • Mechanism: Cephalosporins and vancomycin disrupt bacterial cell wall synthesis.
  • Surgical Protocol: Cefazolin should be redosed every 4 hours during surgery.
  • Drug of Choice: Vancomycin for active MRSA infections.
  • Fetal Safety: Most antibiotics cross the placenta; some can impact fetal development; caution needed during pregnancy with certain antibiotics.