ANTIBIOTIC SUSCEPTIBILITIES OF BACTERIA ISOLATED WITHIN THE ORAL FLORA OF FLORIDA BLACKTIP SHARKS: GUIDANCE FOR EMPIRIC ANTIBIOTIC THERAPY

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Objective. Identify the bacteria present and extent of multi-drug resistance in the oral flora of live blacktip sharks in order to provide definitive microbiologically based guidance for appropriate empiric antimicrobial therapy for severe shark bite victims Background. Several studies have identified pathogenic bacteria in marine animals, including sharks. Of great concern is the level of antibiotic resistance observed in these studies, including resistance to broad-spectrum antibiotic reserved for multi-drug resistant infections. Methods. Blacktip sharks were caught and released from the beach in South Florida after collecting a swab of its oral cavity. All swabs underwent standard microbiological work-up with identification of organisms and reporting of antibiotic susceptibilities was performed using an automated microbiology system. Results. Results from 18 sharks were analyzed and revealed an average of 2.72 bacterial isolates per shark. Gram-negative bacteria were significantly more common than gram-positive (61 vs 39%, P < 0.001) and the most common organisms were Vibrio sp. (28%), various coagulase-negative Staphylococcus sp. (16%), and Pasteurella sp. (12%). The overall resistance rate was 17% 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 isolates of Staphylococcus aureus were methicillin-resistant. The level of antibiotic resistance observed in Florida blacktip sharks is comparable to that of published literature. Antibiotics with the highest susceptibility rates included fluoroquinolones, 3rd generation cephalosporins and sulfamethoxazole/trimethoprim. Conclusion. The level of antibiotic resistance observed in our study is comparable to that of similarly conducted studies. For severe shark bite victims where the suspected species is blacktip, we recommend empiric antimicrobial with either a fluoroquinolone or combination of a 3rd generation cephalosporin plus doxycycline. Grants. The research was supported by Nova Southeastern University's Health Profession Division Research Grant and St. Mary's Medical Center.