An investigation of the bacterial profile recovered from the oral cavity of sharks, on the coast of KwaZulu-Natal, South Africa.
Date
2016
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Abstract
Shark attacks are a rare occurrence globally; however quick treatment of a contaminated wound is imperative. Failure to treat infections in a timely manner may result in fatalities as marine bacteria have opportunistic qualities. In addition, limited knowledge is available on antibiotic resistance of bacteria associated with marine top-predators. A cross-sectional study was, therefore, performed to investigate the bacterial profile of a shark’s oral cavity. During 2012 to 2013, oral swabs were taken from sharks caught in protective gill-nets along the KwaZulu-Natal coastline in South Africa. Isolates were characterised by Gram-stain morphology and identified using biochemical tests and MALDI-ToF MS (Matrix assisted laser desorption/ionisation time-of-flight mass spectrometer). MICs (minimal inhibitory concentration) were performed using agar dilution against clinically important antibiotics. Data presented includes 205 isolates from 34 sharks. A total of ten species of sharks were caught. Ragged-tooth Carcharias taurus was the most frequently caught at 24% (8/34), the least frequent was smooth hammerhead Sphyrna lewini and copper Carcharhinus brachyurus at 3% (1/34). The highest prevalence of bacterial isolates were found in great white, Carcharodon carcharias (20%), scalloped hammerhead Spyrna lewini (16%) and mako Isurus oxyrhincus (14%) sharks. A Pearson correlation was used to calculate the similarities between sharks based on bacterial assemblages and shark-phylogeny. A trend was seen, however, no statistical significance was found. A plausible connection could be established with a higher sample number. In this study Micrococcus, Staphylococcus, Vibrio and Pseudomonas species rank among the four most frequently found bacteria in sharks. MICs revealed bacterial resistance of 50% to cefuroxime, 38% to ampicillin, 18% to nalidixic acid, 14% to tetracycline, 11% to erythromycin, 10% to ceftriaxone and lowest is 2% to ciprofloxacin. No resistance to gentamicin was found, highlighting its value in wound management. This primary data suggests the presence of clinically important bacteria in sharks transferable to humans, requiring specific treatments regimes.
Description
Master of Science in Environmental Science. University of KwaZulu-Natal, Durban 2016.
Keywords
Sharks--Microbiology--South Africa--KwaZulu-Natal., Marine bacteria--South Africa--KwaZulu-Natal., Marine microbiology--South Africa--KwaZulu-Natal., Antibiotics., Drug resistance in microorganisms., Theses--Environmental science., Shark attacks.