Spondylodiscitis and bacteremia due to Staphylococcus hyicus in an immunocompetent man

Staphylococcus hyicus is a coagulase-variable Staphylococcus spp. well-known by veterinarians since it is the major agent of a severe cutaneous infection in piglets called exudative epidermitis. In other species the symptoms of infection are quite different. Human cases are uncommon but seem to occur more frequently after repeated contacts with farm animals.

We report the case of a 58-year-old man suffering from debilitating subacute lumbar pain, in whom diagnosis of infectious spondylodiscitis was based on spine MRI and positive microbiological results. A strain of S. hyicus was surprisingly isolated from blood cultures and bone biopsy. Identification was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS, Bruker, USA), and the patient was successfully cured with a six-week course of anti-staphylococcal antibiotic regimen.

The prevalence of S. hyicus in human clinical samples is very low, but may be underestimated. This pathogen may enter the bloodstream through a skin injury, and then induce various pyogenic manifestations in people working with farm animals. S. hyicus exfoliative toxins, responsible for dermatological lesions in piglets, seem unable to damage the human epidermis, explaining the absence of cutaneous blisters in the previously reported cases. Precise data about its pathogenicity in humans and the adequate therapy are lacking.