Staphylococcus aureus Pyogenic Spondylodiscitis in a Patient With Rheumatoid Arthritis Receiving Rituximab

We report the case of a 55-year-old woman with seropositive rheumatoid arthritis (RA) treated with methotrexate and rituximab (RTX) who developed severe inflammatory low back pain one month after her fourth RTX cycle. MRI of the lumbosacral spine revealed L4-L5 infectious spondylodiscitis with vertebral endplate destruction, anterior epidural extension, and a right psoas abscess. CT-guided aspiration confirmed methicillin-sensitive Staphylococcus aureus infection. Empirical IV therapy with ciprofloxacin and gentamicin was initiated per local protocol. Following microbiological confirmation, ciprofloxacin was continued as the targeted regimen based on confirmed susceptibility (minimum inhibitory concentration (MIC) ≤ 1 mg/L), and gentamicin was discontinued after five days. Both RTX and methotrexate were temporarily suspended. After four weeks of IV therapy, inflammatory markers normalized, and the patient was discharged to complete a three-month antibiotic course, with a favorable outcome. This case highlights the importance of considering pyogenic spondylodiscitis in RTX-treated patients presenting with acute spinal pain, even in the absence of overt hypogammaglobulinemia.