A rare case of spinal tuberculosis due to Mycobacterium bovis. Is zoonotic tuberculosis underdiagnosed?

We report a rare presentation of Pott's disease caused by M. bovis, suggesting transmission from infected cattle, and only the second case described so far in scientific reports. Noteworthy of this case was that the strain was only isolated on Stonebrink medium, a sodium pyruvate-containing culture medium for the isolation of mycobacteria. This medium is frequently ignored in diagnostic laboratories and in the laboratory manuals of most international health organizations. In general laboratories use a culture medium that contains glycerol, a carbon substrate considered inhibitory for the growth of M. bovis. The use of glycerol-containing medium therefore likely contributes towards underestimating zoonotic tuberculosis. Our case suggests that, in order to improved surveillance efforts for zoonotic TB and increase the notification rate for M. bovis to human TB, the use of pyruvate-containing media should be promoted, particularly in developing countries with a high prevalence of bovine TB, but also through the World Health Organization' (WHO) End TB Strategy and the Roadmap for Zoonotic TB.