Antibiotics are sometimes administered to victims of rattlesnake bites in the hope of preventing infections. Experts in the field recommend that prophylactic antibiotics not be used because secondary infections are rare. Current recommendations are based on a small number of studies conducted in the United States. We decided to reexamine the issue by taking advantage of a large database on snakebites in Arizona. This allowed us to determine how often prophylactic antibiotics were used and whether or not they were effective.
Methods
We obtained data from the Arizona Poison and Drug Information Center electronic medical record, Toxicall. Rattlesnake bites occurring over 18 years (1999-2016) were analyzed according to the descriptors: infection, pus, isolation of bacteria, and antibiotic use.
Results
There were 2748 evaluable patients identified as having rattlesnake bites. The mean number of bite victims was 153 per year. Most (72%) were male. Their ages ranged from 8 months to 91 years. Prophylactic antibiotics were administered to 120 of 2748 (4.4%) victims. There were 27 postbite infections (0.98%) but no deaths. Victims sometimes manipulated the wound sites. Microorganisms were isolated from only 9 patients. Only a Salmonellasp. was of certain reptilian origin; the others were likely of human origin.
Conclusions
This large study supports recommendations that prophylactic antibiotics not be used following rattlesnake bites in the United States. The incidence of postbite infections was low, <1%. All but 1 of the bacteria isolated from the wounds were common inhabitants of human skin and not found in oral secretions of rattlesnakes.
Introduction
The World Health Organization reclassified snake envenomation in 2017 as a neglected tropical disease, thereby raising this common health risk to new prominence.1 The World Health Organization2 estimates that snakes bite 5.4 million people worldwide each year, with 2.7 million envenomations resulting in 81,000 to 138,000 deaths each year. Most are reported from Africa, India, and Latin America. According to the National Institute for Occupational Safety and Health,3 there are 7000-8000 venomous snake bites in the United States each year, resulting in 10,000 visits to emergency departments4 and <5 deaths per year.5 The majority of bites in North America are from copperheads, cottonmouths, and rattlesnakes. The prominent local effects of venomous snake (Viperidae) bites include swelling within 2 hours of the bite, blistering in 2-12 hours, and tissue necrosis within a day. Lymphangitis and local lymphadenopathy may occur as well.6 These local signs, along with systemic coagulopathies and shock, are sometimes indistinguishable from effects of infection (Figure 1).
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-Jessica A. August, MD, Keith J. Boesen, PharmD, CSPI, Nicholas B. Hurst, MD, F. Mazda Shirazi, MD, Stephen A. Klotz, MD
This article originally appeared in the November issue of The American Journal of Medicine.
