146.1 🎓 醫孞生版

146.1.0.1 📌 䞀頁重點

  • 䟝動物分:
    • Dog (80% bites): Pasteurella canis, S. aureus, anaerobes, Capnocytophaga
    • Cat (15%): Pasteurella multocida (60-70%), S. aureus, Bartonella (cat scratch)
    • Human: Eikenella corrodens, viridans strep, S. aureus, anaerobes (Bacteroides), HBV/HCV/HIV transmission risk
    • Bat / Wild animal (Asia, Africa): 狂犬病 rabies
    • Reptile (snake): less infection risk than envenomation
    • Tick: Lyme, RMSF, ehrlichiosis, babesiosis, tularemia, tick paralysis
  • First-line antibiotic (most bites): Amoxicillin-Clavulanate (Augmentin) 875/125 BID × 5-10 d
  • Tetanus prophylaxis assess every bite
  • Rabies PEP for high-risk: bat, dog (unvaccinated in endemic), bite from sick/unknown animal
  • HIV / HBV / HCV PEP for human bite with blood exposure

146.1.0.2 1⃣ 動物咬傷 by Source

146.1.0.2.1 Dog Bites
  • 80% of bites in US
  • Often crushing + tearing
  • Pasteurella canis (~ 25%), S. aureus, S. intermedius, Capnocytophaga canimorsus
  • Capnocytophaga canimorsus: in asplenic + alcoholic + immunocompromised → fulminant sepsis (DIC, gangrene)
146.1.0.2.2 Cat Bites
  • Smaller but deeper punctures → higher infection rate (50-80% vs dog 15-20%)
  • Pasteurella multocida (60-70%) — rapid cellulitis (4-24 hr)
  • Sometimes Bartonella henselae (cat scratch disease — separate entity)
146.1.0.2.3 Human Bites
  • Especially clenched fist (“fight bite”) — MCP joint penetration
  • Eikenella corrodens (Gram - rod) — chronic refractory infection
  • HACEK family
  • Viridans strep, S. aureus, anaerobes (Bacteroides)
  • HIV / HBV / HCV transmission: assess source + recipient
146.1.0.2.4 Monkey Bites
  • Herpes B virus (cercopithecine herpesvirus 1) — fatal encephalitis if untreated
  • PEP with acyclovir / valacyclovir
146.1.0.2.5 Bat Bites / Exposures
  • Rabies risk even if no visible bite (sleeping in cabin with bat)
  • PEP for any bat exposure (better safe than sorry)
146.1.0.2.6 Marine
  • Vibrio vulnificus: æµ·æ°Ž + 肝病 = aggressive cellulitis
  • Mycobacterium marinum: fish tank, swimming pool granuloma
  • Aeromonas hydrophila: freshwater wound

146.1.0.3 2⃣ Wound Management

146.1.0.3.1 Immediate
  1. Copious irrigation (sterile saline, > 200 mL high pressure)
  2. Debridement of devitalized tissue
  3. Avoid primary closure for high-risk wounds:
    • Hand bites
    • Cat bites (any)
    • Bite older than 12 hr
    • Crush / deep / contaminated
  4. Primary closure ok for: face (cosmesis), small superficial dog bites, large clean lacerations < 6 hr
  5. Splint hand bites; immobilize
  6. Elevate to reduce edema
146.1.0.3.2 Tetanus
  • Up-to-date (booster < 10 yr): no boost; minor bites → boost only if > 10 yr; severe/dirty → boost if > 5 yr
  • Not up-to-date / unknown: Tdap + tetanus Ig (TIg) 250 IU IM
  • Td alternative to Tdap if Tdap given recently
146.1.0.3.3 Rabies PEP
  • High-risk: bat, wild carnivore (skunk, raccoon, fox), unvaccinated dog/cat in endemic
  • Bat exposure (even without visible bite) if sleeping in same room
  • Healthy domestic dog/cat: observe 10 days; if becomes ill, vaccinate
  • Not previously vaccinated: HRIG (human rabies Ig) 20 IU/kg infiltrated around wound + 4-dose vaccine (Day 0, 3, 7, 14) (5 doses if immunocompromised: + Day 28)
  • Previously vaccinated: 2-dose vaccine (Day 0, 3); no HRIG
146.1.0.3.4 HIV / HBV / HCV (Human Bites)
  • HIV PEP if source HIV+ or unknown high-risk + blood/saliva exposure → 28 d Truvada + dolutegravir (or similar)
  • HBV: if recipient unvaccinated and source HBsAg+ → HBIG + start HBV vaccine series
  • HCV: no proven PEP; serial monitoring of recipient

146.1.0.4 3⃣ Antibiotic Choice

146.1.0.4.1 First-Line
  • Amoxicillin-clavulanate 875/125 PO BID × 3-5 d prophylaxis OR 5-14 d treatment
  • Covers: Pasteurella, S. aureus (MSSA), Strep, anaerobes, Eikenella
146.1.0.4.2 Alternatives (PCN allergy)
  • TMP-SMX + Metronidazole (or clindamycin) — covers Pasteurella + anaerobes (clindamycin + cipro/levo alternative)
  • Doxycycline for Pasteurella + Eikenella (covers most)
  • Moxifloxacin (covers most pathogens + anaerobes)
146.1.0.4.3 Hospitalized / Severe
  • Ampicillin-sulbactam 3g IV q6h OR Pip-tazo
  • MRSA risk: add vancomycin
146.1.0.4.4 Special
  • Cat bite: amox-clav (Pasteurella); if hand → IV initially
  • Human bite, fight bite hand: amox-clav PO or IV; orthopedic / hand surgery consult
  • Marine wound: doxy + ceftri (Vibrio coverage)
  • Capnocytophaga + asplenic / alcoholic: amox-clav OR ceftri + clinda
146.1.0.4.5 Indications for Prophylaxis (no infection yet)
  • Cat / Human bite, ANY
  • Hand, foot, face, genitalia bites
  • Crush injury
  • Bites in immunocompromised, DM, asplenic
  • Deep, sutured wounds