Cave canem: HBO₂ therapy efficacy on Capnocytophaga canimorsus infections: a case series

Dog bites are a frequent injury, but the incidence and type of lesions vary across countries. Although only few patients develop complications, the treatment of advanced injuries has a considerable medical, social and economic impact. A frequently isolated pathogen in dog bite wounds is Capnocytophaga canimorsus, a bacterium that can cause sepsis or meningitis. Hyperbaric oxygen (HBO₂) therapy has been shown to be useful in treating anaerobic infections, most likely because it creates an inhospitable environment for the bacterium and enhances the patient's immune response.

We present a case series of C. canimorsus infections treated with HBO₂ in adjunction to antibiotic therapy. Furthermore, we tested the in vitro activity of ceftaroline against C. canimorsus, alone and in association with hyperbaric oxygen therapy.

We included nine (9) patients admitted to the surgery department of "A. Cardarelli" Hospital (Naples) after dog bite, from 2010 to 2016. All were initially treated with antibiotics and required transfer to the intensive care unit due to worsening conditions. C. canimorsus was isolated from wounds, and HBO₂ therapy was administered in adjunction to antibiotics, until clinical improvement and microbiological test negativity. We tested the activity of hyperbaric oxygen therapy in adjunction to ceftaroline on cultured plates with C. canimorsus versus ceftaroline alone. Minimal inhibitory concentration was evaluated.

Our findings confirm the utility of HBO₂ therapy after biting injuries. Indeed, increased oxygen supply to the wound (as well as in vitro) may be toxic for bacteria, can improve healing and may improve the effectiveness of antibiotics.