Periprosthetic Joint Infection Caused by Streptococcus equi Subspecies zooepidemicus : The First Reported Case Confirmed by Synovial Fluid Culture
Marjaana Pitkäpaasi, Goran Varda, Juha O. Grönroos, Elisabet Fellman, Kaisa Huotari, Stergios Lazarinis, Marika NordbergBackground
Streptococcus equi subspecies zooepidemicus (SEZ) is a pathogen associated with infections in horses. It can occasionally transmit and cause clinical infections in humans. Even though the bacterium is an opportunistic pathogen, human infections are often severe such as meningitis, septicemia, endocarditis, and septic arthritis.
Case Report
We report a unique case of synovial fluid culture–confirmed periprosthetic joint infection (PJI) caused by SEZ. The patient had undergone a total knee arthroplasty due to osteoarthritis. Five months postoperatively, she was admitted to the hospital with fever and clinical signs of PJI of the knee. The bacterial culture of the synovial fluid and blood cultures revealed SEZ. The 16S rRNA polymerase chain reaction (16S rRNA PCR) and culture of perioperative synovial tissue samples confirmed the same bacterium. Within 48 h of the onset of PJI symptoms, an operation with DAIR (debridement, antibiotics, and implant retention) was performed and followed by 12 weeks of antibiotic therapy. The prosthetic joint was preserved, and the patient had fully recovered with no signs of infection relapse at the 2‐year follow‐up. Two weeks prior to the PJI symptoms, the patient had visited a horse stable, where one of the horses had symptoms of an upper respiratory infection.
Conclusion
We present the first case of synovial fluid culture–confirmed PJI caused by SEZ described in the literature. SEZ can be transmitted from horses to humans and cause serious infections, including PJI. The bacterium should be kept in mind when investigating acute infections, including PJI, in people who encounter horses due to their profession or hobbies.