Chief Complaint: “Spider Bite”
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Transcript 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)
- Brown Recluse (Loxosceles reclusa)
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
Brown Recluse
Dwells in low traffic areas: Attics,
basements and wooodpiles
Brown Recluse
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
Brown Recluse Bite
Fevers, chills, weakness, HA,
nausea/vomiting, myalgias, maculopapular
rash, and leukocytosis
Rare complications: Hemolytic Anemia,
DIC, thrombocytopenia, Hemoglobinuria,
Renal Failure
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
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
Black Widow Bites
Unremarkable local lesions
Oftentimes systemic reactions
Proximally spreading pain
Localized diaphoresis
Black Widow Spider Bite
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.
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
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
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
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
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
With increasing prevalence of CAMRSA
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
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
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
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