Lactococcus garvieae Periprosthetic Joint Infection in a Cattle Rancher with a Total Knee Arthroplasty: A Novel Reservoir Transmission.

Introduction: Periprosthetic joint infection (PJI) remains a challenging complication of joint replacement surgery. With the more frequent use of immune modifying drugs and dietary changes in human populations, the resultant blunting of immune defenses allows for infections with less common organisms.

Case Report: Lactococcus garvieae is an anaerobic, gram-positive coccus with reservoirs in fish and domesticated farm animals. Only two prior cases of PJI due to L. garvieae have been reported, both with reported marine transmission. We report a case of L. garvieae associated PJI in a cattle rancher with the first reported case of transmission from a bovine reservoir. The PJI was associated with intra-articular rice body formation, and the diagnosis confirmed with the aid of next generation DNA sequencing. A successful two stage exchange was performed. We propose a novel transmission mechanism with microbe entry via direct hematogenous inoculation during the patient's duties as a rancher.

Conclusion: When an unusual organism is detected in a PJI, the treatment team should research the host reservoir(s) of the organism and correlate with the patient's exposure risk. While contamination of cultures is possible, a thorough investigation should be performed prior to that assumption. This reinforces the basic concept that a careful history remains vital when treating an unusual infection presentation. Next generation DNA sequencing is a useful confirmatory tool in establishing the offending organism. Lastly, the identification of rice bodies should raise suspicion for infection. Although not always associated with infection, efforts should be redoubled to identify or rule out a causative micro-organism(s).