Infections After Shark Attacks in Australia

Shark bites are rare, even in Australia. Two cases presenting in a 2-week period to adjacent hospitals, and with similar infectious problems, prompted this report. Case 1. A 24-year-old plumber who had partaken freely of alcoholic beverages, was bet $80 by friends to swim to a pole 30 meters from shore in the Parramatta River. This is a large river in Western Sydney, 30 km from the ocean. He completed the swim naked, but on the way felt a sturdy bump on the leg. On reaching shore he was bleeding from the left leg and right scrotum. At Westmead Hospital he was stable and well. He was found to have an arc of puncture wounds on the dorsal and ventral aspects of his left thigh and a right scrotal laceration penetrating the tunica dartos and tunica vaginalis, with the testis and epididymis protruding. A forensic dental opinion was that the wounds were caused by a shark bite, probably that of a bronze whaler (Fig. 1). The wound was debrided and sutured after the testis was replaced.Fig. 1: Arc mark on medial surface of left thigh of Case 1, a pattern characteristic of shark bite. Each tooth mark is ∼1.5 cm in diameter.Swabs from the wound grew Vibrio parahaemolyticus and Aeromonas caviae. He was treated with a 5-day course of cefotaxime, flucloxacillin and metronidazole given intravenously, followed by oral ciprofloxacin and doxycycline, and made an uneventful recovery. He won his bet. Case 2. A 7-year-old boy was standing in knee-deep seawater, with his family and 60 tourists, at Lord Howe Island, New South Wales, while feeding the large local king fish with a fisherman. A 1.5-meter-long reef shark approached and the fisherman declared it safe. Immediately the boy fell down with the shark biting his left calf and trying to drag him away. The fisherman jumped on the shark punching it and drove it off. The boy was bleeding profusely from the calf. The calf was bandaged, iv fluids were started, and the boy was flown by air ambulance to the Royal Alexandra Hospital for Children. He was pale but not in shock, with a 20-cm-long, 5-cm-deep laceration and loss of sensation in the left foot. At operation it was found the shark had transected the distal belly of the child's gastrocnemius and soleus muscles and had severed the tibial vessels and nerve and the great saphenous vein. The area was debrided and the anterior tibial nerve, tibial vessels and muscle belly were repaired. The wound was left open, and iv antibiotic and morphine therapy was commenced. After 48 h the wound "smelled fishy," and the boy was febrile at 39.5°C. Necrotic tissue was further debrided and antibiotic therapy was changed to iv gentamicin, metronidazole and oral ciprofloxacin. Swabs grew Vibrio alginolyticus, Aeromonas hydrophila, a Proteus species, two species of Klebsiella (Klebsiella oxytoca and Klebsiella pneumoniae), Citrobacter freundii and an Enterococcus species. The fever normalized immediately. Several further debridements were necessary, but skin grafting was avoided and wound closure was achieved after 10 days. The patient suffered night terrors and dreamed he was suspended from a hook on the ceiling. He designed a conveyor belt fish-feeding machine that operated from the safety of the shore. Sensation returned to his foot, and his mental state improved with psychiatric help and with time. Discussion. There are 370 species of shark in the world; most attacks on hmans are attributable to 4 species, the white shark, oceanic white tip, dusky shark and bronze whaler. Bronze whalers often feed at night, which was when the first case was attacked. Other sharks may bite humans if provoked or, as in Case 2 in error when hunting fish.1 Shark bites, like other injuries sustained in saltwater, are often infected with Vibrio and Aeromonas species. Vibrios have been grown from the teeth of sharks,2, 3 and Vibrio carchariae [Greek "carcharias" = shark, but also scoundrel, rogue] was grown from the infected calf wound of an 11-year-old girl in South Carolina, who sustained an injury identical to that of Case 2.4 Vibrios, particularly Vibrio vulnificus, can cause a rapidly progressive cellulitis or myositis, sometimes within hours of injury in saltwater. Infections with Aeromonas species are a feature of both fresh and saltwater injuries.5 Other Gram-negative bacilli, Staphylococcus aureus and anaerobes can all infect shark bites.2, 3 Cefotaxime and metronidazole intravenously or ciprofloxacin orally are appropriate initial empiric therapy, to be changed according to the in vitro susceptibilities of cultured organisms. Jennifer A. Royle, M.B. David Isaacs, M.D. Gillian Eagles, M.B. Danny Cass, M.D. Nicole Gilroy, M.B. Sharon Chen, M.B. David Malouf, M.B. Christopher Griffiths, A.M., R.F.D.