Staphylococcus Aureus Bacteremia in Patients with Rheumatoid Arthritis - Data from the Prospective INSTINCT Cohort

Objectives: Patients with rheumatoid arthritis (RA) are considered to be at increased risk of severe infections. We here describe the clinical characteristics, course and outcome of RA patients with Staphylococcus aureus bacteremia (SAB).

Methods: We conducted a post hoc analysis of data from a German bi-center prospective SAB cohort study (period 2006-2014). Patients were followed-up for one year. Primary and secondary outcomes were survival time and osteoarticular infection (OAI).

Results: A total of 1069 patients with SAB were analyzed, with 31 patients suffering from RA. RA patients showed significantly more often OAI (15/31 patients, 48% vs. 152/1038, 15%), disseminated infection (12/31, 39% vs. 164/1038, 16%) and severe sepsis/septic shock (12/31, 39% vs. 235/1038, 23%). Day-30 mortality in RA patients was 36% (vs. 19% in non-RA patients, p = 0.034), and day 90 mortality was 58% (vs. 32%, p = 0.003). Multivariate analyses confirmed RA to be an independent risk factor for death (HR 2.3, 95% CI 1.4-3.7) and OAI (OR 4.2, 95% CI 1.8-9.8).

Conclusions: Patients with RA exhibit a complicated SAB course and a high mortality, their management is challenging. Adequate antibiotic treatment, prompt invasive diagnostic and therapeutic procedures like joint lavage or surgery are of pivotal importance. Joint damage due to RA may confer a higher risk of acquiring OAI than immunosuppression.