Staphylococcus lugdunensis Bacteraemia With Bilateral L4–L5 Facet Joint Septic Arthritis Following Lumbar Radiofrequency Ablation: A Case Report

Staphylococcus lugdunensis is a virulent coagulase-negative Staphylococcus that can cause invasive bloodstream and deep-seated infection, behaving more like Staphylococcus aureus than commensal skin flora. A 73-year-old patient with chronic low back pain underwent bilateral lumbar medial branch and sacroiliac joint radiofrequency ablation. Over seven weeks, they developed progressively worsening low back pain with bilateral radicular symptoms, saddle anaesthesia, constipation, and acute urinary retention, without fever. C-reactive protein was markedly elevated with a normal white cell count and low procalcitonin. Magnetic resonance imaging demonstrated bilateral L4-L5 facet joint septic arthritis with a small paraspinal collection, without discitis, vertebral osteomyelitis, epidural abscess, or cauda equina compression. Admission blood cultures and computed tomography-guided L4-L5 facet aspiration both yielded S. lugdunensis, confirming bacteraemic bilateral facet joint septic arthritis. Empirical intravenous therapy was initiated and streamlined to intravenous flucloxacillin after susceptibility results and documented microbiological clearance; four weeks of intravenous therapy were completed from the first negative blood culture, followed by prolonged oral step-down therapy. The patient improved clinically, with declining inflammatory markers, radiological interval improvement, and approximately 80% pain reduction without recurrent neurological deficits. Progressive post-procedural pain with neurological red flags after lumbar radiofrequency ablation warrants urgent evaluation for deep spinal infection, even in the absence of fever, and S. lugdunensis bacteraemia should prompt systematic assessment for invasive foci and prolonged antistaphylococcal therapy. This case highlights the need to investigate progressive post-procedural pain with neurological red flags for deep spinal infection, even in the absence of fever, and to treat S. lugdunensis bacteraemia as a true pathogen requiring evaluation for invasive foci and prolonged antistaphylococcal therapy.