Antibiotic Susceptibilities of Bacteria Isolated within the Oral Flora of Florida Blacktip Sharks: Guidance for Empiric Antibiotic Therapy

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.

Shark attack-related injuries: Epidemiology and implications for plastic surgeons

“…Special attention should be paid to any areas of devitalized tissue in order to minimize the risk of delayed infection, which is extremely common for these wounds. 12,21 Numerous bacteria have been described to cause infections after shark bites with the most common being Vibrio and Aeromonas species. 8,12,21 Aside from a typical cellulitis or abscess, these bacteria have also been reported to cause a rapidly progressive cellulitis or myositis within the first several hours post-attack.…”

“…12,21 Numerous bacteria have been described to cause infections after shark bites with the most common being Vibrio and Aeromonas species. 8,12,21 Aside from a typical cellulitis or abscess, these bacteria have also been reported to cause a rapidly progressive cellulitis or myositis within the first several hours post-attack. 21,22 Serial wound evaluation is warranted to monitor for necrotizing infections, especially in the case of Vibro vulnificans or Vibro parahaemolyticus.…”

“…8,12,21 Aside from a typical cellulitis or abscess, these bacteria have also been reported to cause a rapidly progressive cellulitis or myositis within the first several hours post-attack. 21,22 Serial wound evaluation is warranted to monitor for necrotizing infections, especially in the case of Vibro vulnificans or Vibro parahaemolyticus. [21][22][23] The plastic surgeon might also be called to assist with the debridement of an infected shark wound and should not hesitate to debride widely to eradicate these difficult to treat infections.…”

“…21,22 Serial wound evaluation is warranted to monitor for necrotizing infections, especially in the case of Vibro vulnificans or Vibro parahaemolyticus. [21][22][23] The plastic surgeon might also be called to assist with the debridement of an infected shark wound and should not hesitate to debride widely to eradicate these difficult to treat infections.…”

“…Empiric antibiotic treatment is recommended for all shark bites. 12,21,23 The choice of antibiotics should include coverage for not only Vibrio and Aeromonas species, but for Staphylococcal and Streptococcal infections as well.…”