First report of prosthetic joint infection due to Mycoplasma capricolum

Mycoplasma capricolum is a pathogen almost exclusively found in goats, which causes contagious caprine pleuropneumonia, a highly contagious respiratory disease of small ruminants. Herein, we report the first case of prosthetic joint infection (PJI) caused by M. capricolum. The patient was a goat herder who had been implanted with a total knee prosthesis 9 years earlier. He presented to the emergency department with fever and swelling in the knee. A biochemical analysis of the joint fluid was highly suggestive of a PJI but the culture remained negative for bacteriological and mycobacterial growth. The patient was discharged with a diagnosis of inflammatory knee osteoarthritis; however 2 weeks later, the patient was referred to the emergency department again due to joint effusion. Small unidentifiable pinpoint-sized colonies grew on the chocolate agar medium from the joint fluid and blood samples after more than 1 week of incubation. Application of 16S ribosomal RNA gene sequencing to the colonies was able to identify the organism as M. capricolum. To the best of our knowledge, this is the first case of M. capricolum PJI, and it highlights the utility of using molecular methods in diagnosing implant-associated infections.