Brown recluse spider bite: Difference between revisions

Revision as of 00:08, 17 November 2015

Brown recluse range (yellow area)

Brown recluse

Venom contains variety of cytotoxic enzymes causing necrotic wound, principally Hyaluronidase and Sphingomyelinase-D
- Hyaluronidase: facilitates the penetration of the venom into tissue but does not induce lesion development.
- Sphingomyelinase-D: causes necrosis and lesion formation by initiating the release of pro-inflammatory mediators (thromboxanes, leukotrienes, prostaglandins, and neutrophils)

Bite is initially painless
Mild reaction
- Most common
- Mild erythematous lesion that later becomes firm and heals without scar
Severe reaction
- Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling
- Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
- By day 3 or 4 hemorrhagic area may become ecchymotic
  - Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
- By end of first week ecchymotic area may become necrotic w/ eschar formation
Systemic effects
- Rare
- Occur predominantly in children 24-72hr after the bite
  - Include nausea/vomiting, fever, arthralgias, DIC, rhabdo, renal failure

Local wound care
Abx are indicated only if signs of infection exist; secondary infections are uncommon
Although some texts recommend Dapsone, it has been shown to be of limited benefit and is associated with hemolysis in G6PD patients and als methemoglobinemia

Authors:

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 ===Mechanism===
-*Venom contains variety of cytotoxic enzymes causing necrotic wound
+*Venom contains variety of cytotoxic enzymes causing necrotic wound, principally Hyaluronidase and Sphingomyelinase-D
+**Hyaluronidase: facilitates the penetration of the venom into tissue but does not induce lesion development.
+**Sphingomyelinase-D:  causes necrosis and lesion formation by initiating the release of pro-inflammatory mediators (thromboxanes, leukotrienes, prostaglandins, and neutrophils)
 ==Clinical Features==