What is the preferred treatment for the bite of a brown recluse spider?

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Elsevier ClinicalKey Clinical Overview

Treatment Mainstay of therapy in the United States is supportive care with expectant observation for both dermatologic and systemic loxoscelism: First line supportive care for dermatologic manifestations Most cutaneous lesions heal with local wound care without aggressive medical treatment Local wound care Antihistamine for itching Aspirin Rest, cool compress, Avoid aggressive cooling of the skin to avoid exacerbation of tissue damage Loose immobilization of affected extremity Wound cleaning Recommend general wound care several times daily until wound heals Tetanus prophylaxis when indicated Debridement of necrotic wounds in consultation with wound care specialist or surgeon Timing of wound care is debated; most specialists perform it once the wound margins are well defined without advancing margins after 1 to 2 weeks Vacuum-assisted wound closure (negative pressure wound therapy) Animal studies indicate accelerated wound healing rates with this novel, largely experimental therapy Hyperbaric oxygen therapy Consider for any rapidly deteriorating wounds in consultation with medical toxicologist and wound care/hyperbaric medicine specialist; evidence for efficacy is conflicting Care for systemic loxoscelism Serial monitoring for renal impairment and progressive anemia is indicated in patients with significant hemolysis Begin renal protective measures in patients with signs of hemolysis or rhabdomyolysis Fluid replacement to maintain adequate urine output Urinary alkalinization to maintain urinary pH above 6 or 6.5 Can often be achieved by fluid repletion alone Add sodium bicarbonate if target pH is not achieved with fluid repletion Consider mannitol to maintain urine output if it is not established by fluid repletion Pressor support to maintain renal perfusion Packed RBC transfusions for significant anemia Dialysis is very rarely required for patients with progressive deterioration in renal function resulting from intravascular hemolysis and rhabdomyolysis No consensus treatment specific to loxoscelism exists:

Treatment Common treatments that may be recommended in consultation with medical toxicologist or surgical subspecialist despite limited evidence of efficacy in humans include the following: Dapsone Dapsone is a sulfone antibiotic with polymorphonuclear leukocyte inhibitory properties and can theoretically antagonize the local inflammatory response triggered by venom Anecdotal evidence exists for benefit in some animal models when dapsone is begun within 12 hours of envenomation; Few experts advocate use for adults with proven brown recluse envenomation for potentially necrotic wounds when oral administration is started within 48 to 72 hours Baseline assessment for glucose-6-phosphate dehydrogenase deficiency is indicated before administration; dapsone is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency and in children Adverse effects are a major concern with dapsone administration; some degree of hemolysis occurs in most patients; methemoglobinemia, aplastic anemia, peripheral neuropathy, and cholestatic jaundice are other serious adverse effects Hyperbaric oxygen therapy Theory is that this therapy can inactivate some contents of venom by oxidation and improve wound healing by increasing oxygen tension in tissue Evidence for specific use with brown recluse envenomations is limited in humans; there are reports of good outcomes in some uncontrolled human trials Some experts advocate use for rapidly deteriorating wounds, whether or not known cause is Loxosceles envenomation Barotrauma and oxygen toxicity are potential adverse effects of treatment

2.

Elsevier ClinicalKey Clinical Overview

Treatment Severe Cases Dapsone use is controversial. Animal studies have produced mixed results. In one uncontrolled human study, patients treated with dapsone required less surgery and had better clinical outcomes. Some studies have indicated that to have any efficacy, dapsone must be initiated in the first 36 hours after the bite. The use of systemic corticosteroids is advocated by some authorities, but six animal studies and human studies have failed to demonstrate any definitive benefit on lesion size or progression with corticosteroids. Brown recluse specific antivenin exists but must be administered within the first 24 hours.

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Hadanny A, Fishlev G, Bechor Y, Meir O, Efrati S. Advances in Skin & Wound Care. 2016;29(12):560-566. doi:10.1097/01.ASW.0000504578.06579.20.

Publish date: December 4, 2016.

BACKGROUND: Bites by Loxosceles spiders (also known as recluse spiders or brown spiders) can cause necrotic ulcerations of various sizes and dimensions. The current standard of care for brown spider bites includes analgesics, ice, compression, elevation, antihistamines, and surgical debridement. Hyperbaric oxygen therapy (HBOT) in the treatment of brown spider bites has been administered in the early stage of ulceration, or 2 to 6 days after the bite. Unfortunately, the diagnosis of spider bite-related ulcers is often delayed and weeks or months may elapse before HBOT is considered. OBJECTIVE: To evaluate the effect of HBOT on nonhealing wounds caused by brown spider bites in the late, chronic, nonhealing stage. METHODS: Analysis of 3 patients with brown spider-bite healing wounds treated at The Sagol Center for Hyperbaric Medicine and Research in Israel. Patients presented 2 to 3 months after failure of other therapies including topical dressings, antibiotics, and corticosteroids. All patients were treated with daily 2 ATA (atmospheres absolute) with 100% oxygen HBOT sessions. RESULTS: All 3 patients were previously healthy without any chronic disease. Their ages were 30, 42, and 73 years. They were treated once daily for 13, 17, and 31 sessions, respectively. The wounds of all 3 patients healed, and there was no need for additional surgical intervention. There were no significant adverse events in any of the patients. CONCLUSIONS: Microvascular injury related to brown spider bites may culminate in ischemic nonhealing wounds even in a relatively young, healthy population. Hyperbaric oxygen therapy should be considered as a valuable therapeutic tool even months after the bite.