Infected intravascular catheters are currently the most common source of Staphylococcus aureus bacteremia [1–4]. Serious complications include endocarditis and deep-seated metastatic infections in different organs [2,5–12]. Spinal epidural abscess as a complication of S. aureus bacteremia associated with infected intravenous catheters is rare [10,11].
We report a case of acute spinal epidural abscess complicating methicillin-resistant S. aureus (MRSA) bacteremia associated with an infected peripheral intravenous catheter in a 60-year-old woman admitted for treatment of congestive heart failure.
A 60-year-old woman with history of coronary artery disease, ischemic cardiomyopathy with poor left ventricular function (left ventricular ejection fraction of 15%), valvular heart disease with moderate mitral regurgitation, tricuspid regurgitation, mild aortic regurgitation, and renal insufficiency presented to emergency department because of worsening leg edema and shortness of breath. She had been admitted on several previous occasions owing to congestive heart failure. She was admitted again for treatment of congestive heart failure. She was afebrile on admission. Her white blood cell count was 7900 × 109 cells/L.
A peripheral intravenous catheter was inserted to the right antecubital area on admission for the administration of furosemide and dobutamine for the treatment of congestive heart failure. A new peripheral venous catheter was inserted over the left forearm 4 days later. After 2 days, the patient developed fever (38.3°C) with chills. The white blood cell count was 21,700 × 109 cells/L. She complained of pain at the intravenous catheter site at her left forearm, which was tender. The catheter was removed. Two sets of blood cultures were obtained. She was empirically treated with intravenous clindamycin because she was allergic to penicillin. All four bottles of blood cultures eventually grew MRSA. Clindamycin treatment was then changed to vancomycin. She had no signs of infective endocarditis such as conjunctival hemorrhages, Janeway lesions, Osler nodes, or Roth spots. The heart murmurs were unchanged. Both transthoracic two-dimensional echocardiogram and transesophageal echocardiogram (TEE) revealed no lesions compatible with vegetation.
Five days after developing fever and 2 days after intravenous vancomycin was started, she complained of lower back pain. There was tenderness at the L4–S1 spine area. An MRI scan of the lumbosacral spines revealed lesions compatible with spinal epidural abscess at level L4–S1 measuring approximately 3 × 1 cm, slight spinal canal stenosis, impingement of the external root on the left, and also mild early discitis of the disc at L5–S1 (Fig. 1). She underwent lumbar laminectomy of L5–S1, discectomy, and drainage of the spinal epidural abscess. Cultures of abscess obtained at operation grew MRSA. Both isolates from blood cultures and epidural abscess were susceptible to vancomycin and rifampin.
After surgery, she continued to receive intravenous vancomycin, and rifampin was added. Her back pain gradually improved. She was discharged with no neurologic deficit and continued her treatment vancomycin and rifampin for a total of 6 weeks. She was asymptomatic at the 3-month follow-up visit.
Endocarditis as a complication of intravenous catheter-associated S. aureus bacteremia has been known for over a quarter of a century [5,12]. A recent prospective study using TEE reported that 23% of patients with intravascular catheter-associated S. aureus bacteremia had endocarditis . Metastatic deep-seated infections including osteomyelitis are known complications of intravascular catheter-associated S. aureus bacteremia [8–11]; two retrospective studies reported prevalence of 19% and 20% [8,9]. However, spinal epidural abscess is a very rare complication [10,11].
Bernhardt and colleagues  reported a 47-year-old man who had S. aureus bacteremia complicating an infected peripheral intravenous catheter. Three weeks after appropriate 2-week antibiotic treatment, he was readmitted because of back pain and weakness of lower extremities. Vertebral osteomyelitis of T6–8 vertebrae and epidural abscess due to S. aureus of the same phage type as the original blood isolate were found. Korzets and colleagues  reported that two patients undergoing long-term hemodialysis treatment developed spinal epidural abscess (one also had vertebral osteomyelitis) complicating MRSA bacteremia associated with infected central intravenous catheters. The diagnosis and treatment were delayed and both patients died. Bollensen et al.  reported a case of a 55-year-old man with intravenous catheter-associated bacteremia complicated by epidural abscess and discitis at the C5–6 level, but the infecting organism was not identified. The diagnosis was delayed, resulting in quadriplegia. In our patient, the epidural abscess with early discitis but no osteomyelitis was diagnosed early. Antimicrobial therapy and surgical drainage were instituted promptly, resulting in cure without sequelae.
In patients with intravenous catheter-associated S. aureus bacteremia, TEE should be done to detect possible vegetations [12,14]. In addition, the patient should be carefully observed for symptoms and signs of deep-seated infections. New onset of back pain is the most important symptom, and localized vertebral tenderness is the most reliable physical sign of vertebral osteomyelitis and epidural abscess [11,15–17]. MRI is the diagnostic test of choice [11,15–17]. Prognosis is excellent if the diagnosis is made and appropriate antibiotic therapy with surgical drainage is instituted promptly, as in our patient. Delayed diagnosis and treatment can result in paralysis and even death [11,13].
This patient’s S. aureus bacteremia was associated with an infected peripheral intravenous catheter. It should be emphasized that complications such as endocarditis and deep-seated infections from S. aureus bacteremia associated with infected peripheral intravenous catheters are not different from those associated with infected central venous catheters or permanently implanted intravascular catheters [2,5–9].
We chose to treat our patient with vancomycin in combination with rifampin. There have been reports of suboptimal therapeutic response in vancomycin therapy of serious MRSA infection such as endocarditis [18,19]. Rifampin has excellent activity against S. aureus and penetrated abscess well .
In summary, in patients with intravascular catheter-associated S. aureus bacteremia, even though TEE showed no evidence of endocarditis, the patient should be observed closely for evidence of other deep-seated metastatic infections. Acute onset of back pain with localized tenderness of the spine should raise the suspicion of epidural abscess or vertebral osteomyelitis. MRI is the diagnostic test of choice. Prompt surgical drainage and antimicrobial therapy can result in cure without sequelae.
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