Infection, as a complication of rheumatoid arthritis(RA), has attracted more and more attention from rheumatologists. Here, we present the first case of RA with hip joint infection which is driven by infection with Prevotella denticola.The anaerobic bacteria infection was identified by metagenomic next-generation sequencing (mNGS).

We describe the case of a 56-year-old female with a history of RA who was admitted for intense hip joint pain and intermittent fever following long-term oral glucocorticoid(GC).

Although the blood and hip joint effusions culture for aerobic and anaerobes organisms was negative, we considered that she was tend to a clinical diagnosis of hip joint infection, so she was started on empirical antibiotic therapy, but is ineffective for her. Prevotella denticola was isolated by mNGS from hip joint effusion which was obtained by ultrasound-guided puncture and was resistant to initial antimicrobial therapy. Finally, the adjustment of antimicrobial therapy enabled therapeutic success.

Patients with RA have significantly higher risk of infection than others, however, Prevotella denticola infection of the hip joint has not been reported. Consequently, the combination of ultrasound-guided puncture and mNGS technology in order to the accurately and timely recognition and treatment of joint infection in RA is necessary to prevent evolution of complications, which is worthy of further clinical promotion.