Adult Native Vertebral Osteomyelitis Clinical Guideline
Commentary by Jeffrey Gudin, MD
Native vertebral osteomyelitis (NVO) can be a difficult disease to spot in a patient, especially given its nondescript symptoms, such as recalcitrant back pain, fever, and elevated inflammation. However, new guidelines present a comprehensive framework for proper clinical diagnostics and treatment of the condition. NVO is the result of hematogenous seeding of the adjacent disc space from a distant focus.1,2 While a relatively rare spinal condition, NVO is the most common form of hematogenous osteomyelitis for patients 50 to 70 years of age.3 And yet, NVO can be a difficult condition to spot in a patient, let alone treat.
Because of its nondescript symptoms, patients with NVO can go undiagnosed for months or misdiagnosed altogether as having some kind of degenerative process, according to Jeffrey Gudin, MD, a director of pain and palliative care at the Icahn School of Medicine at Mount Sinai Hospital in New York, New York.
“Vertebral osteomyelitis in adults has the potential to be a devastating condition with extended morbidity and mortality consequences,” including permanent spinal cord injury and septicemia. Because of this, doctors should be aware of the most trusted approach to effectively diagnosing and treating the disease, but given the scant inventory of cohort-based studies about NVO, many important clinical decisions have lacked professional consensus up to this point.
Fortunately, the Infectious Diseases Society of America (IDSA) recently published a clinical practice guideline for treating NVO. The result of a comprehensive, evidence-based assessment by the society’s 11-member professional panel, the IDSA’s new guidelines provide a detailed, thorough consensus on some of the most controversial questions surrounding NVO treatment, like how to utilize safe, timely antimicrobial therapy, when to use immediate surgical intervention, or how to definitively establish a treatment failure.
Clinical Diagnostics of NVO
“Clinicians who evaluate patients with back pain should consider an infectious etiology and NVO in patients with systemic signs or symptoms,” said Dr. Gudin. According to the IDSA guidelines, doctors should suspect a diagnosis of NVO in patients that present with new or worsening back or neck pain, along with these signs or symptoms:
- Elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP)
- Bloodstream infection or infective endocarditis
NVO could also be suspected in patients with or without back pain, who have fever, new neurological symptoms, or a Staphylococcus aureus bloodstream infection within the previous year. 1,4,5 The evidence is weak for these contexts, however.
If a patient is suspected of having NVO, the guidelines recommend:
- Giving a pertinent medical and motor/sensory neurologic examination
- Obtaining 2 sets of blood cultures (aerobic and anaerobic) and baseline ESR and CRP
- Performing a spinal MRI
- If MRI is unattainable, obtaining a combination spine gallium/Tc99 bone scan, computed tomography scan, or a positron emission tomography scan (weak evidence)
- Patients with subacute NVO residing in endemic areas for brucellosis may require blood cultures and serologic tests for Brucella species.
- Patients with suspected NVO at risk for fungal infection may require fungal blood cultures (weak evidence).
- Patients with subacute NVO at risk for Mycobacterium tuberculosis NVO may require a purified protein derivative (PPD) test or an interferon-γ release assay (weak evidence).
An image-guided aspiration biopsy (a needle aspiration from disc space, using computed tomographic (CT) or fluoroscopic guidance) is essential before putting a patient on antimicrobial therapy, particularly if serologic tests have not confirmed the diagnosis.
However, image-guided aspiration biopsy is not recommended for patients:
- With suspected NVO that have S. aureus, S. lugdunensis, or Brucella species bloodstream infection
- With suspected subacute NVO and strongly positive Brucella serology
Most patients are hemodynamically stable and have no neurological symptoms. However, immediate initiation of empiric antimicrobial therapy and surgical intervention are recommended for patients with neurological compromise, with or without impending sepsis or hemodynamic instability.
Therapy regimens should include coverage against staphylococci, including:
- methicillin-resistant S. aureus (MRSA)
- gram-negative bacilli
While such a regimen might include vancomycin and a third- or fourth-generation cephalosporin, the guidelines note that an empiric antimicrobial therapy can depend on various factors, like allergy, intolerance, epidemiological risk, et cetera. However, empiric antifungal and antimycobacterial therapy is not appropriate in most situations.
Properly Defining a Treatment Failure
Microbiologically confirmed persistent infection despite targeted antimicrobial therapy is the recommended definition of treatment failure.6,7 Granted, there is still no clear definition of treatment failure in NVO patients, but the guidelines caution against using “persistent pain, residual neurologic deficits, elevated markers of systemic inflammation, or radiographic findings,” alone to establish treatment failure. Those adverse outcomes could be more related to the patient’s comorbidities, premorbid functional status, or extant of initial infection. The intent is to prevent overestimation of treatment failure in NVO patients, which can lead to unnecessary medical and surgical interventions.8,9
The full Infectious Diseases Society of America guidelines can be found here.
The expert panel that composed these guidelines consisted of experts in infectious diseases, spine orthopedic surgery, and neuroradiology. Accordingly, the IDSA has its own policy regarding conflicts of interest, as each individual member of the expert panel appropriately submitted any relevant financial interests that could be construed as an actual, potential, or apparent conflict of interest. No limiting conflicts of interest were identified.