Abstract
Sharks possess a variety of pathogenic bacteria in their oral cavity that may potentially be transferred into humans during a bite. The aim of the presented study focused on the identification of the bacteria present in the mouths of live blacktip sharks, Carcharhinus limbatus, and the extent that these bacteria possess multi-drug resistance. Swabs were taken from the oral cavity of nineteen live blacktip sharks, which were subsequently released. The average fork length was 146 cm (±11), suggesting the blacktip sharks were mature adults at least 8 years old. All swabs underwent standard microbiological work-up with identification of organisms and reporting of antibiotic susceptibilities using an automated microbiology system. The oral samples revealed an average of 2.72 (±1.4) bacterial isolates per shark. Gram-negative bacteria, making up 61% of all bacterial isolates, were significantly (p<0.001) more common than gram-positive bacteria (39%). The most common organisms were Vibrio spp. (28%), various coagulase-negative Staphylococcus spp. (16%), and Pasteurella spp. (12%). The overall resistance rate was 12% for all antibiotics tested with nearly 43% of bacteria resistant to at least one antibiotic. Multi-drug resistance was seen in 4% of bacteria. No association between shark gender or fork length with bacterial density or antibiotic resistance was observed. Antibiotics with the highest overall susceptibility rates included fluoroquinolones, 3rd generation cephalosporins and sulfamethoxazole/trimethoprim. Recommended empiric antimicrobial therapy for adult blacktip shark bites should encompass either a fluoroquinolone or combination of a 3rd generation cephalosporin plus doxycycline.
Highlights
Florida consistently boasts the highest number of shark attacks in the world, accounting for nearly one-third of all incidents in 2013 with about 20% caused by blacktip sharks (C. limbatus) based on witness and victim accounts, and to some extent scientific determination [1,2,3]
In the case of a shark bite, antibiotic therapy should target the bacteria transferred from the oral flora of the shark into the victim’s wound
Shark capture and sampling Blacktip sharks were caught with a surf rod and a sixty-five pound fishing line with a 12/0 circle hook off of beaches in Martin and Palm Beach Counties in Florida, which have been previous identified by research as high-risk cluster areas of shark attacks along the Florida coast [21]
Summary
Florida consistently boasts the highest number of shark attacks in the world, accounting for nearly one-third of all incidents in 2013 with about 20% caused by blacktip sharks (C. limbatus) based on witness and victim accounts, and to some extent scientific determination [1,2,3]. These bites within Florida waters are rarely fatal, victims of severe bites are at risk for subsequent infection and related complications due to entry of bacteria from the shark’s oral cavity into the open wound. With the global rise of antimicrobial resistance, these recommendations may no longer be appropriate
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