section name header

Info


A. Concernsnavigator

  1. Rabies (see below)
  2. Deep infections
    1. Fascitis and tendinitis - may be subtle, especially in the hand
    2. Myositis
  3. Wound Management
    1. Good irrigation and drainage
    2. Debridement rarely needed since bites usually relatively new
  4. Sepsis
    1. Local inflammation in most patients
    2. Occasional patients will have no local symptoms
  5. Tetanus [2]
    1. Important causes of death in underdeveloped nations (180,000 deaths/year worldwide)
    2. Particularly problematic in neonates, and in pregnant mothers
    3. Must be considered in all animal bites
    4. Toxoid should be given to all patients who have not had boosters within 5 years
    5. Immune globulin and toxoid to all patients not previously immunized
  6. Cat Scratch Disease
  7. Snake Bites (see below)
  8. Animal bites account for ~1% of emergency department visits in USA

B. Rabies [3,4] navigator

  1. Lyssaviruses
    1. Rabies is a member of lyssavirus genus of rhabdovirus family
    2. Seven different genotypes of lyssaviruses
  2. Especially with dogs, bats, raccoons, skunks
  3. Pathogenesis
    1. Bites by rabid animal
    2. Invariably fatal if not treated early
    3. Should be considered in all unprovoked attacks by animals
    4. Increased risk in wild animals
    5. Must be considered in any patient with rapidly progressive encephalitis
    6. Presentation with motor problems, paresthesias, pharyngitis
    7. Patient may not recall being bitten by an animal
    8. Most domestic animals are immunized
    9. When in dobut, immunize (± rabies globulin) and contact local health department
    10. Several vaccines are available and should be given [5]
    11. Human diploid cell vaccine should be avoided, as it has 6% incidence of serum sickness
  4. Rabies Treatment and Vaccination [5,8]
    1. Patients may receive pre- or post-exposure prophylaxis
    2. Postexposure prophylaxis includes human rabies immune globulin (Imogam Rabies-HT®)
    3. Postexposure prophylaxis should be given when animal involved cannot be observed [8]
    4. A 1mL dose of one of the 3 available rabies vaccines should also be given
    5. For previously unvaccinated persons, repeat vaccines on days 3,7,14,28 after first dose
    6. If pre-exposure vaccination occurred, then boosters on days 0 and 3 recommended
    7. Pre-exposure prophylaxis for high risk persons involves dosing on days 0,7 and 21 or 28
    8. RabAvert® (from chick embryos) has 100% efficacy and appears safer than others [12]
    9. Severe egg allergy is a contraindication to using RabAvert
    10. Imovax® prepaired from human fibroblasts causes serum sickness in 6% of recipients
    11. RVA (Rabies Vaccine Adsorbed) from fetal rhesus diploid lung cells is also available

C. Other Organisms navigator

  1. Depends primarily on source
  2. Consider rabies with dogs, bats, raccoons, skunks (see above)
  3. Cats and Dogs [6,13]
    1. About 10% of bites will become infected
    2. Pasteurella multocida and/or canis - rapid development (within 6-10 hrs) post bite
    3. Streptococci have been reported in ~40-50% of cases
    4. Staphylococcus aureus - slower development (>24 hours) post bite (local skin flora)
    5. Bartonella - cat scratch disease; mainly in immunocompromised [13]
    6. Fusobacterium
    7. Bacteroides
    8. Corynebacterium
    9. Neisseria weaveri and other species
    10. Capnocytophaga canimorsus - formerly called "DF-2" organism (may be less common)
    11. Porphyromonas
    12. Prevotella
  4. Enterobacteriaceae and Pseudomonas are uncommon
  5. Infections Transmitted by Cat and/or Dog Bites [1,6,13]
    1. Bacteria: Bartonella [13], Brucella, Campylobacter, Leptospira, Tularemia, Salmonella
    2. Other Bacteria: Plague, Non-plague Yersinia, Chlamydia psittaci, Bordetella bronchoseptica
    3. Rickettsia: Q fever (Coxiella), Ehrlichia, Rocky Mountain Spotted Fever
    4. Nematode Infections (cutaneous, visceral)
    5. Cryptosporidium, Echinocockus, Tapeworms, Heartworms, Toxoplasmosis, Giardia
    6. Fungi: Dermatophytes, Sporotrichosis, Microsporium
    7. Viral: Rabies, Cowpox
  6. Human Bites [12]
    1. Usually due to direct bite or to "fight bite" (clenched fist injury)
    2. Clenched fist injury usually with 3-5 mm laceration on dorsum of hand or overlying MCP joint
    3. Thorough examination of area for possible extension of infections
    4. Mainly normal oral flora and skin flora
    5. Staph aureus, streptococci common
    6. Eikenella corrodens
    7. Gram negative bacilli
    8. Anaerobes: Peptococcus, Peptostreptococcus, Fusobacterium, Bacteroides ssp.
    9. Human bites are particularly concerning, and must be followed carefully

C. Treatment navigator

  1. Prophylaxis with antibiotics of questionable value for low risk bites and patients
    1. No proven benefit
    2. Risk of antibiotic therapy are usually small
    3. Recommended in moderate bites and all cat bites
    4. Antibiotics should definitely be used in all severe bites (and cat bites)
  2. Treatment of Mild Wounds
    1. Augmentin® (amoxicillin-clavulanate) 500mg po tid for 10-14 days
    2. Alternatives include Cefuroxime (Ceftin®), Doxycycline, TMP/SFX (Bactrim®)
    3. Ceftriaxone 1-2gm im q24 hours may also be given (requires parenteral administration)
  3. Serious Infections
    1. Surgical Intervention - debridement and cultures
    2. Intravenous Antibiotics are generally recommended (consider IV outpatient therapy)
    3. Must cover Gram Positive Organisms, anaerobes, and Pasteurella
    4. Ampicillin/Sulbactam (Unasyn®) or Ticarcillin/Clavulanate (Timentin®)
    5. Clindamycin + Cefuroxime OR Cefoxitin may be used as well
    6. Ceftriaxone has poor anaerobic coverage and should be used cautiously as single agent
    7. Parenteral antibiotics should be given for a minimum of 3-5 days in most cases
    8. Single dose IV with high dose oral antibiotics may be considered
  4. Other oral agents
    1. Quinolones: Ofloxacin 400mg po bid or Ciprofloxacin 500mg po bid
    2. Sulfa (Bactrim®, Septra®) - 1 DS tablet po bid - variably active against capnocytophaga
    3. Clindamycin 600mg po tid - not effective against Pasteurella
  5. Other considerations
    1. Tetanus prophylaxis - is immunologulin needed ?
    2. Rabies prophylaxis is very important (see below)
    3. Thorough cleaning of wound and continued care after initial hospital visit
    4. Patient education on signs of worsening infection
    5. Surgical debridement may be required
    6. Capnocytophaga infection may be fatal, particularly in asplenic patients [7]

D. Snakebites [9,10]navigator

  1. 6000-8000 venomous snakebites and 6-12 fatilities per year in USA
    1. Usually appear as two fang punctures (1-3 fangs possible)
    2. Local swelling and necrosis
    3. Venom is rarely immediately life threatening unless a vein is punctured directly
    4. Pain and local swelling usually develop within 5 minutes
    5. Victims are typically males aged 17-27
  2. Etiology (USA)
    1. Most bites occur in soutwestern USA
    2. Rattlesnakes - most common bites, 95% of fatalities
    3. Copperheads - seldom require antivenom due to weak venom
    4. Cottonmouths (water moccasin) - intermediate strength venom
    5. Coral snake bites also occur infrequently (deep South and west to Arizona)
    6. Classed as pit vipers due to heat sensitive pits between eyes for sensing prey
    7. Overall, 120 snakes in USA and 20 are venomous
  3. Venom Types
    1. Typically complex mixtures of proteins 6-100kD causing various reactions:
    2. Hemotoxic: pain, edema, weakness, numbness, ecchymoses, coagulopathy, fasciculation
    3. Severe hemotoxic reaction: disseminated intravascular coagulation (DIC), sepsis, death
    4. Neurotoxic: ptosis, weakness, paresthesia, diplopia, dysphagia, sweating, salivation
    5. Severe neurotoxic reaction: hyporeflexia, respiratory depression, paralysis, death
  4. Rattlesnake Bite
    1. Local Injury
    2. Coagulopathies (thrombocytopenia, DIC)
  5. First Aid
    1. Avoid: tight (arterial) tourniquets, wound incision, ice
    2. Patient should avoid excess activity, immobilize bitten extremity, transport to hospital
    3. Wide, flat constriction band proximal to block applied to restrict only venous and lymphatic flow (~20 mm Hg pressure)
    4. Leave band in place until antivenom is administered
    5. Any impairment of arterial flow will increase tissue necrosis
    6. Immobilize injured part of body in functional position below heart level
    7. Venom extractor may be beneficial if applied within 5 minutes of snake bite
    8. Leave extractor in place for 30 minutes
    9. Transport to hospital
  6. Hospital Evaluation and Treatment
    1. Admit to emergency department
    2. Clean wound and administer tetanus toxoid or tetanus immune globulin if indicated
    3. Intravenous fluid given
    4. Blood testing from sample drawn from unaffected extremity
    5. Hematology: CBC with differential, PT, PTT, fibrinogen, fibrin degradation products (FDP), blood type and cross-match
    6. Chemistry: serum electrolytes, glucose, BUN, creatinine, LFTs, creatine kinase (CK), urinalysis (free protein, hemoglobin, myoglobin), stool hemoccult
    7. Electrocardiography (ECG) and arterial blood gas for patients with underlying disease
    8. Observation for at least 12 hours recommended for hemotoxic venoms
    9. Observation for at least 24 hours recommended for neurotoxic venoms
  7. Antivenom (Antivenin) [11]
    1. Ovine CroFab® is more effective and better tolerated than equine Antivenin®
    2. CroFab® is the Fab fragments of immune globulin from immunized sheep
    3. Sheep immunized to Western and Eastern Diamondback and Mojave rattlesnakes, and also immunized to cottonmouth
    4. Should be given within 6 hours of rattlesnake bite
    5. Initial dose is 4-6 vials IV infused over 60 minutes
    6. Eastern coral snakebites require Antivenin
    7. Specific antivenom for exotic snakebites Arizona Poison Center (520-626-6016)
  8. Information is available in USA at 877-377-3784 and 800-222-1222

References navigator

  1. Tan JS. 1997. Arch Intern Med. 157(17):1933 abstract
  2. Roper MH, Vandelaer JH, Gasse FL. 2007. Lancet. 370(9603):1947 abstract
  3. Noah DL, Drenzek CL, Smith JS, et al. 1998. Ann Intern Med. 128(11):922 abstract
  4. Warrell MJ and Warrell DA. 2004. Lancet. 363(9413):959 abstract
  5. Rabies Vaccines. 1998. Med Let. 40(1029):64 abstract
  6. Talon JA, Citron DM, Abrahamian FM, et al. 1999. NEJM. 340(2):85 abstract
  7. Parsonnet J and Versalovic J. 1999. NEJM. 340(23):1819 (Case Record) abstract
  8. Moran GJ, Talan DA, Mower W, et al. 2000. JAMA. 284(8):1001 abstract
  9. Juckett G and Hancox JG. 2002. Am Fam Phys. 65(7):1367 abstract
  10. Gold BS, Dart RC, Barish RA. 2002. NEJM. 347(5):347 abstract
  11. CroFab Snake Antivenom. 2001. Med Let. 43(1107):55 abstract
  12. Clark DC. 2003. Am Fam Phys. 68(11):2167 abstract
  13. Koehler JE and Duncan LM. 2005. NEJM. 353(13):1387 (Case Record) abstract