Micrognome

A death from shark attack off the Western Australian coast this week prompted a colleague to ask about infections following shark bites. Just this month, a Brazilian group published a paper on shark oral bacteria.  At the beginning of their research methods they describehow they captured four bull and five tiger sharks 20km off the Recife coast with longlines. That’s field work you can sink your teeth into.

Perhaps the most surprising bit of the report is that no researchers were harmed in these experiments.

The following bacteria were found around the teeth of the captured sharks:

Gram negative

• Enterobacter cloacae, E.aerogenes
  
• Citrobacter freundii, C. koseri, C.farmeri
  
• Proteus mirabilis, P. vulgaris
  
• Moellerella wisconcensis
  
• Providencia alcalifaciens
  
• Escherichia coli
• Leclercia adecarboxylata
• Pseudomonas aeruginosa, Ps. stutzeri
• Vibrio parahaemolyticus, Vibrio spp.
• Acinetobacter sp.

Gram positive

• Staphylococcus epidermidis, S.sciuri, S.warneri, S.hominis, S.xylosus
  
• Streptoccus (viridans group)
• Enterococcus species

The first reported analysis of bacteria from the mouth of a shark investigated the bacterial flora of a great white and found several marine Vibrios. The presence of these species in the mouths of bull and tiger sharks captured off the coast of northeastern Brazil is interesting, and reinforces the need for  antibiotics effective against marine bacteria such as Vibrio species when treating shark-induced injury.

Not that this is going to happen every day. Shark attacks are rare in the overall scheme of things, fatal attacks occurring in this part of the world only once every few years. Interesting, then that Recife has seen an unusually high rate of shark attacks in recent years. It is also a good place to capture sharks. For those that really need to know the gory details, an international record of shark attacks has been maintained at the University of Florida. The record contains over 4000 investigations with an overall mortality of shark attack at 8.3%.

There are some great resources for worldwide shark attack maps including

• Shark Attack Map Interactive
• Global Shark Attack Map