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Chief Complaint: “Spider Bite”

Chief Complaint: “Spider Bite”. Jill R. Tichy, PGY III 10/2/2009. Spider bites are rare medical events. Typically single lesions Do not occur in multiple family members Influence of Geographic Location Medically significant bites occur: - Black Widow ( Latrodectus mactans )

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Chief Complaint: “Spider Bite”

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  1. Chief Complaint:“Spider Bite” Jill R. Tichy, PGY III 10/2/2009

  2. Spider bites are rare medical events • Typically single lesions • Do not occur in multiple family members • Influence of Geographic Location • Medically significant bites occur: - Black Widow (Latrodectus mactans) - Brown Recluse (Loxosceles reclusa)

  3. Presumptive Diagnosis of Spider Bite • A spider must be observed inflicting the bite • The spider was recovered, collected, and properly identified by an expert entomologist

  4. Brown Recluse • Dwells in low traffic areas: Attics, basements and wooodpiles

  5. Brown Recluse

  6. Brown Recluse Bite • Venom contains Sphingomyelinase B, a dermonecrotic factor • Initial bite is painless • Within hours site is painful and pruritic with central induration with zones of ischemia and erythema • Most resolve within a few days • In severe cases erythema spreads and center lesion becomes necrotic and hemorrhagic

  7. Brown Recluse Bite • Fevers, chills, weakness, HA, nausea/vomiting, myalgias, maculopapular rash, and leukocytosis • Rare complications: Hemolytic Anemia, DIC, thrombocytopenia, Hemoglobinuria, Renal Failure

  8. Treatment of Brown Recluse Bite • Local Cleansing, Cold Compresses, Analgesics, Anti-histamines, Tetanus vaccine • Equivocal data for Dapsone within 48-72 hours of bite may halt progression of necrosis

  9. Black Widow (Latrodectus mactans) • Webs in dark spaces: barns, under rocks, plants, garages • Prevalent in southeastern US • Most common in summer to early autumn • Initial bite unnoticed; May have two small fang marks; No local necrosis • Alpha-latrotoxin binds to nerves and causes depletion Ach and Norepi • Within 60 minutes of bite, painful cramps ensue • Symptoms can wax and wane for several days

  10. Black Widow Bites • Unremarkable local lesions • Oftentimes systemic reactions • Proximally spreading pain • Localized diaphoresis

  11. Black Widow Spider Bite

  12. Black Widow Envenomation • Local pain may be followed by localized or generalized severe muscle cramps and weakness. • In severe cases, nause/ vomiting, dizziness and respiratory difficulties may follow. • Abdominal Pain may mimic a surgical abdomen (peritonitis) • Chest pain may be mistaken for myocardial infarction • Labored breathing • HTN • Life-threatening reactions are generally seen only in small children and the elderly.

  13. Widow Spider Bite treatment • Local Wound Care; Ice Packs • Benzodiazepines • Equine Antivenom (Antivenin) reserved severe cases usually seen in children and elderly due to high risk of serum sickness and anaphylaxis

  14. Treatment of Spider bites • Most cause limited local inflammation: Analgesia and Antihistamine • Brown Recluse: Standard local wound care and treat superinfection • Black Widow: IV opiates; Benzodiazepines; Antivenin if severe reaction in children or elderly • Consider other etiology unless definitive diagnosis

  15. Differential is broad • Community-acquired methacillin-resistance Staphylococcus Aureus (CA-MRSA) • Early Lyme Disease: Erythema Migrans • Southern tick-associated rash illness (STARI) • Herpes Zoster and Herpes Simplex (herpetic whitlow) • Scorpion Bites • Poison Ivy/ Oak • Other insect bites and stings • Cutaneous Lymphoma/Sarcoma

  16. CA-MRSA • 1990s MRSA infections detected in the community in persons with no contact to health care system • Strains demonstrate a global, geographic variation • Small DNA cassettes mediating methacillin resistance differ from those associated with hospital acquired strains

  17. CA-MRSA: antibiotic therapy • No clinical trials for optimal antibiotic therapy • Avoid use of Clindamycin when local rates of resistance exceed 10-15% among MRSA isolates causing skin and soft tissue infections • Anecdotal concern for Streptococcus A resistance to sole therapy of Doxycycline or Bactrim • Possible recurrence rate is > 10% • ? Intranasal bactroban “decolonization” efficacy

  18. With increasing prevalence of CA-MRSA • Management of skin and soft tissue infections requires knowledge of local rates of MRSA infection • See UNC antibiogram for Community Isolates for Staphylococcus spp. • Follow-up is essential

  19. UNC antibiogram for community isolate of Staphylococcus spp; 2008 • All strains: 2216; coag neg: 145; ORSA: 1144; OSSA: 1072 • Clindamycin: 66% strain susceptible to ORSA/ 74 % to OSSA • Doxycycline: 94% susceptible to ORSA • Bactrim: 94% susceptible to ORSA

  20. CA-MRSA • Abscess +/- Purulent/Necrotic Skin lesion = I&D • Culture Purulent Material • Lesions < 5cm I&D sufficient • Lesions > 5cm and/or systemic signs of infection = I&D + Abx

  21. References • Harrison’s Principals of Internal Medicine; 17th edition • NEJM; “Skin and Soft-Tissue Infections Caused by MRSA”; July 26, 2007 • Consultant. Vol. 46 No. 12 Necrotic Lesions: Spider Bite-or Something Else? • Journal of American Board of Family Medicine; 17: 220-226; 2004 • UNC Antiobiogram 2008 • Uptodate.com

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