A Rare Case of Staphylococcus Caprae Periprosthetic Hip Infection with Unusual Clinical Presentation.

Introduction: Total hip arthroplasty (THA) surgeries are rapidly increasing due to an aging population, leading to an increase in degenerative hip osteoarthritis. However, 1% of these patients go through prosthetic joint infection (PJI), which gives rise to implant failure with prolonged periods of patient incapacitation and higher mortality risk. Case Report: In this article, we report an unusual case of a 62-year-old male who developed a PJI 7 months after a THA. The patient complained of groin, buttock pain, and swelling. He underwent MRI examination, which revealed the presence of a voluminous three-lobed formation with liquid content located around the prosthesis. After several attempts where microbiological samples reported negative results, a microbiological sample came out positive for Staphylococcus Caprae at the time of femoral component sonication. S. caprae is a Gram-positive bacillus belonging to the Staphylococcus spp. It is most commonly found as a commensal in goats and sheep, but it is a rare pathogen in human infections. The patient underwent two-stage revision surgery, resulting in the total resolution of the infection. Conclusion: Staphylococcus Caprae still remains an unusual cause of infection. We report the 11th hip PJI due to S. caprae successfully treated with a two-stage exchange protocol.