Chapter 121. Trauma and Envenomation from Marine Fauna

The population growth along coastal areas has made exposure to hazardous marine fauna increasingly common. The popularity of home aquariums generates additional exposures inland. Marine fauna can inflict injury through direct traumatic bite or envenomation, usually via a stinging apparatus.

Marine trauma includes bites from sharks, barracudas, moray eels, seals, crocodiles, needlefish, wahoos, piranhas, and trigger fish. Shark bites may also cause substantial tissue loss with hemorrhagic shock and delayed infection. Minor trauma is usually due to cuts and scrapes from coral that can cause local stinging pain, erythema, urticaria, and pruritus. Marine wounds can be infected with routine skin flora, such as Staphylococcus and Streptococcus, along with bacteria unique to the marine environment. The most serious halophilic organism is the gram-negative bacillus Vibrio, which can cause rapid infections marked by pain, swelling, hemorrhagic bullae, vasculitis, and even necrotizing fascitis and sepsis. Immunosuppressed patients, particularly those with liver disease, are susceptible to sepsis and death (up to 60%) from Vibrio vulnificus. Another bacterium, Erysipelothrix rhusiopathiae, implicated in fish handler's disease, can cause painful, marginating plaques after cutaneous puncture wounds. The unique marine bacterium Mycobacterium marinum, an acid-fast bacillus, can cause a chronic cutaneous granuloma 3 to 4 weeks after exposure.

Numerous invertebrate and vertebrate marine species are venomous. The invertebrates belong to 5 phyla: Cnidaria, Porifera, Echinodermata, Annelida, and Mollusca.

The 4 classes of Cnidaria all share stinging cells, known as nematocysts, which deliver venom subcutaneously when stimulated. The most common effect is pain, swelling, pruritus, urticaria, and even blistering and necrosis in severe cases. The Hydrozoans include hydroids, Millepora (fire corals), and Physalia (Portuguese man-of-war). The latter causes a linear erythematous eruption and rarely can cause respiratory arrest, possibly from anaphylaxis. In addition to local tissue injury, the Scyhozoans (true jellyfish) include Atlantic Ocean larval forms that can cause a persistent dermatitis under bathing suits lasting days after exposure (Seabather's eruption). The Cubozoans (box jellyfish), in particular Chironex fleckeri in Australia and Chiropsalmus in the Gulf of Mexico, can cause death after severe stings. A Hawaiian species, Carybdea, has been implicated in painful stings but no deaths. Another Australian box jellyfish, Carukia barnesi, can cause Irukandji syndrome, characterized by diffuse pain, hypertension, tachycardia, diaphoresis, and even pulmonary edema. The most innocuous cnidaria are the Anthozoans (anemones) that occasionally cause a mild local reaction.

Porifera (the sponges) can produce a stinging, pruritic dermatitis. Spicules of silica or calcium carbonate can become embedded in the skin along with toxic secretions from the sponge. Echinodermata include sea urchins and sea stars. Sea urchin spines produce immediate pain with trauma; some contain venom that leads to erythema and swelling. Retained spines can lead to infection and granuloma formation. The crown-of-thorns sea star, Acanthaster planci, has sharp rigid spines that cause burning pain and local inflammation. Annelida include bristle and fire worms, which embed bristles in the skin, causing pain and erythema. Mollusca include gastropods and octopuses. Both the Indo-Pacific cone shell, Conus, and the blue-ringed octopus, Hapalochalena, can deliver paralytic venom that can quickly leads to respiratory paralysis.

Vertebrate envenomations are primarily due to stingrays (order Rajiformes) and spined venomous fish (scorpion fish, lion fish, catfish, and weeverfish). The stingray whip tail has venomous spines, which puncture or lacerate causing an intense painful local reaction. The spines of venomous fish have glands that force venom into the wound after puncture and cause local pain, erythema, and edema. Retention of a spine can lead to infection.

1. Copiously irrigate lacerations, punctures and bite wounds; explore for foreign matter and débride devitalized tissue. Soft tissue radiographs or ultrasound may help locate foreign bodies, which usually require removal especially if intraarticular. Leave lacerations open for delayed primary closure. Update tetanus, if needed.

2. Prophylactic antibiotic therapy is not indicated for routine minor wounds in healthy patients but may be considered in selected patients (Table 121-1). Antibiotic therapy for infected wounds is first directed toward likely pathogens and later by culture and sensitivity results. Cover Staphylococcus and Streptococcus species with a first generation cephalosporin, such as cephalexin 500 milligrams 4 times daily or cefazolin 1 to 2 grams every 8 hours, or clindamycin 300 milligrams po/600 milligrams IV 4 times daily, or doxycycline 100 milligrams po/IV twice daily. Addition of a third-generation cephalosporin, such as ceftriaxone 1 gram IV daily or cefotaxime 2 grams IV every 8 hours, or a fluoroquinolone, such as levofloxacin 500 milligrams PO/IV daily will cover ocean related infections from Vibrio. A fluoroquinolone or third-generation cephalosporin, or trimethoprim-sulfamethoxazole double strength, 1 tablet PO twice each day, or imipenem, 500 milligrams IV every 6 hours, will cover fresh water infections from Aeromonas. Granulomas from Mycobacterium marinum require several months of treatment with clarithromycin or rifampin plus ethambutol.

3. See Table 121-2 for early treatment of envenomations.