When an underestimated zoonosis and antimicrobial resistance collide: Corynebacterium ulcerans

In the European region, diphtheria is now rarely suspected in patients presenting with upper respiratory tract symptoms. C. ulcerans is the underestimated zoonosis that is replacing C. diphtheria infections in industrialised countries, but extensive human and animal prevalence studies are lacking. The range of hosts that can act as reservoirs for C. ulcerans is very broad, companion pets currently being the main source of human infection. We report a case of macrolide-resistant C. ulcerans infection with no apparent zoonotic transmission and outline the efforts required for public and zooprophylactic management of these cases. We describe the main critical issues to be addressed to comprehensively tackle this zoonosis in the future.