Antibiotic susceptibilities of bacteria isolated within the oral flora of Florida blacktip sharks: guidance for empiric antibiotic therapy

PLoS One. 2014 Aug 11;9(8):e104577. doi: 10.1371/journal.pone.0104577. eCollection 2014.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bacteria / drug effects*
  • Bacteria / isolation & purification*
  • Drug Resistance, Bacterial
  • Florida
  • Mouth / microbiology*
  • Practice Guidelines as Topic*
  • Sharks / microbiology*

Substances

  • Anti-Bacterial Agents

Grants and funding

The research was supported by Nova Southeastern University’s Health Profession Division Research Grant and St. Mary’s Medical Center. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.