Case Presentation: A 59 year-old woman with uncontrolled diabetes mellitus and end-stage kidney disease on hemodialysis presented with altered mental status and a suprapatellar abscess. Following irrigation and debridement, her course was complicated by septic shock. She was found with high-grade methicillin-sensitive Staphylococcus aureus bacteremia, and her blood cultures ultimately sterilized with IV cefazolin therapy. Despite hemodynamic stabilization and resolution of leukocytosis, the patient remained stuporous. Further investigation revealed septic emboli on brain MRI as likely culprits. In the following days, her mental status gradually improved such that she could answer questions. While she had been evaluated by five different providers on weekend coverage, a new complaint of left lower extremity paralysis was only identified by the primary team. An emergent MRI of the spine revealed osteomyelitis and an epidural abscess at C5-6. Resultant cord compression and edema were also noted. The patient was urgently transferred to an affiliate hospital with the capability of neurosurgical intervention.
Discussion: Finding S. aureus bacteremia in the hospital setting should provoke vigilance for its sequelae, especially in patients with risk factors such as diabetes mellitus and kidney disease on hemodialysis. S. aureus infection is the most common cause of spinal epidural abscesses through hematogenous spread; however, it is still rare and easily missed with an incidence of only 0.2—2.8 per 10,000 hospital admissions. An MRI with gadolinium contrast is the most sensitive modality for epidural abscess diagnosis but unfortunately, many other clinical and laboratory findings are nonspecific if MRI is not possible. The typical symptoms of fever, back pain, and focal neurologic deficit are not always observed at presentation and are uncommonly found together. An altered mental status makes the diagnosis challenging when sensorimotor function or a review of systems cannot be reliably assessed. If the patient cannot follow commands, observation of bladder and bowel dysfunction or depressed reflexes can support a diagnosis of spinal cord injury, although non-specific for an epidural abscess. For these reasons, around half of patients with an admission for epidural abscess are initially misdiagnosed, and 4—22% of patients will suffer irreversible paralysis in part due to delays in appropriate treatment.
Conclusions: Patients with S. aureus bacteremia are at particularly high risk for morbid or fatal complications and require vigilant monitoring, even when blood cultures have sterilized. The potential for epidural abscess should not be forgotten, although diagnosis can prove elusive. In this setting, continued surveillance is imperative to assess for clinical developments, especially those undetected prior to recovery from altered mental status.