A Rare Case of Orf Virus Precipitating Methicillin-Resistant Staphylococcus Aureus Bacteremia Superinfection Leading to Native Hip Joint Septic Arthritis.

Introduction: Orf disease, or Ecthyma contagiosum, is a zoonotic skin infection caused by the orf virus. The orf virus belongs to the family parapoxvirus and is commonly seen in sheep, goats, and deer. Transmission to humans is most commonly caused by direct contact with infected animals or fomites. Septic arthritis is a serious orthopaedic condition that requires prompt identification and early medical treatment. Septic arthritis is often precipitated by bacteremia, which allows for hematogenous spread of the bacterial load to the affected joint. Without prompt effective treatment, septic arthritis can lead to significant long-term sequelae and disability.

Case report: This case report presents a rare occurrence of methicillin-resistant Staphylococcus aureus septic arthritis of a native hip joint in a 56-year-old Caucasian male, precipitated by Orf virus and subsequent bacteremia. The patient presented with lower back and left-sided groin pain that was progressively worsening, which he first noticed 3 weeks prior. He was a full-time sheep farmer and had been diagnosed with Orf virus on his hand 6 weeks before his current presentation. In addition, he had psoriasis and was taking a single biological immunosuppressive agent, although he did not have any active psoriatic lesions at this time. After a thorough clinical, biochemical, and radiographical assessment, a diagnosis of the left hip septic arthritis was made. He was promptly treated with surgical irrigation and debridement, and targeted intravenous antibiotic therapy. He responded well to the multidisciplinary approach to his care, had a dramatic improvement in his symptoms, and regained his hip range of motion.

Conclusion: Immunocompromised patients need to be thoroughly assessed when presenting with joint pain. Zoonotic infections, especially around farm workers, can precipitate certain viral illnesses, in this case Orf virus, which can predispose patients to bacterial superinfection and subsequent septic arthritis. Prompt clinical, biochemical and radiographical assessment are essential to making an accurate diagnosis to allow for early surgical irrigation and debridement in patients affected by septic arthritis.