Protracted Course of Staphylococcus lugdunensis Septic Arthritis in Native Knee Joint.

Staphylococcus lugdunensis is a coagulase-negative bacteria of the Staphylococcus family. It is a highly invasive organism with similar virulence to Staphylococcus aureus. It is commonly associated with bacteremia and infections of the skin, soft tissues, joints, and bones. Those with indwelling medical devices are at the highest risk of infection due to biofilm formation. Instances of native joint infections are exceedingly rare. We describe a case of a 72-year-old female with multiple comorbidities presenting with native right knee joint septic arthritis from S. lugdunensis. Due to treatment noncompliance secondary to latent social determinants of health, she faced a complicated and protracted clinical course that was treated with inpatient intravenous antibiotics and outpatient oral doxycycline. Few cases of native joint infections with S. lugdunensis have been documented, and to our knowledge, the impact of treatment noncompliance on the sequelae of septic arthritis with this organism has not been reported. Socioeconomic factors and comorbidities have been shown to increase a patient's risk for an extended joint infection with S. lugdunensis.