Staphylococcus lugdunensis (S lugdunensis) is a species of coagulase-negative Staphylococcus (CoNS) and a constituent of human skin flora. Unlike other strains of CoNS, however, S lugdunensis has gained notoriety for virulence that resembles Staphylococcus aureus (S aureus). S lugdunensis is now recognized as an important nosocomial pathogen and cause of prosthetic device infections, including vascular catheter infections. We present a case of persistent S lugdunensis bacteremia occurring in a patient on hemodialysis (HD) without any implanted prosthetic materials.
Case Presentation
A 60-year-old man with a history of uncontrolled type 2 diabetes mellitus (T2DM) and end-stage renal disease on home HD via arteriovenous fistula (AVF) presented to the emergency department (ED) for evaluation of subacute progressive low back pain. His symptoms began abruptly 2 weeks prior to presentation without any identifiable trigger or trauma. His pain localized to the lower thoracic spine, radiating anteriorly into his abdomen. He reported tactile fever for several days before presentation but no chills, night sweats, paresthesia, weakness, or bowel/bladder incontinence. He had no recent surgeries, implanted hardware, or invasive procedures involving the spine. HD was performed 5 times a week at home with a family member cannulating his AVF via buttonhole technique. He initially sought evaluation in a community hospital several days prior, where he underwent magnetic resonance imaging (MRI) of the thoracic spine. He was discharged from the community ED with oral opioids prior to the MRI results. He presented to West Los Angeles Veterans Affairs Medical Center (WLAVAMC) ED when MRI results came back indicating abnormalities and he reported recalcitrant pain.
On arrival at WLAVAMC, the patient was afebrile with a heart rate of 107 bpm and blood pressure of 152/97 mm Hg. The remainder of his vital signs were normal. The physical examination revealed midline tenderness on palpation of the distal thoracic and proximal lumbar spine. Muscle strength was 4 of 5 in the bilateral hip flexors, though this was limited by pain. The remainder of his neurologic examination was nonfocal. The cardiac examination was unremarkable with no murmurs auscultated. His left upper extremity AVF had an audible bruit and palpable thrill. The skin examination was notable for acanthosis nigricans but no areas of skin erythema or induration and no obvious stigmata of infective endocarditis.
The initial laboratory workup was remarkable for a white blood cell (WBC) count of 10.0 × 103/µL with left shift, blood urea nitrogen level of 59 mg/dL, and creatinine level of 9.3 mg/dL. The patient’s erythrocyte sedimentation rate (ESR) was 45 mm/h (reference range, ≤ 20 mm/h) and C-reactive protein level was > 8.0 mg/L (reference range, ≤ 0.74 mg/L). Two months prior the hemoglobin A1c had been recorded at 9.9%.
Given his intractable low back pain and elevated inflammatory markers, the patient underwent an MRI of the thoracic and lumbar spine with contrast while in the ED. This MRI revealed abnormal marrow edema in the T11-T12 vertebrae with abnormal fluid signal in the T11-T12 disc space. Subjacent paravertebral edema also was noted. There was no well-defined fluid collection or abnormal signal in the spinal cord. Taken together, these findings were concerning for T11-T12 discitis with osteomyelitis.