Fever and Back Pain

The case is that of a patient presenting with back pain and fever. 

As with every case in medicine, it is important to keep your thinking broad initially and based on the gathered data, to narrow your focus. 

Further history revaled that this patient had a 3 week history of lower back pain, increasing in severity and persistence. He is a known IVDU and had been using up until 2 weeks ago. He also had associated fevers and sweats, but no other localizing symptoms of infection or other system specific complaints.

Sidenote:

There are certain bacteria associated with what is mixed with IV drugs:

- Toilet water is associated with enteric gram negative bacilli

- Lime juice is associated with candida

On exam, he was febrile, but hemodynamically stable. His exam was significant for poor dentition with perigingival erythema. His MSK examination did NOT have any point tenderness over his spine.  The remainder of his physical exam was normal including no signs of systemic diseases/syndromes.

At this point, the differential for his back pain and fever included:

Infectious

- Vertebral Osteomyelitis

- Paravertebral/epidural abscess

- Pyelonephritis

- Intraabdominal infection with referred pain

Non-infectious

- Pancreatitis

- Malignancy ie bony mets, plasmacytoma, etc.

- Connective Tissue Disease

- Mechanical back pain

- Disc disease

MRI revealed L4-5 Vertebral Ostseomyelitis. Blood cultures were persistently positive for MSSA. ECHO is pending.

Dx: Vertebral Osteomyelitis secondary to MSSA bacteremia, presumed secondary to IVDU.

A word on Vertebral OM aka Discitis

Origin
- Hematogenous spread

- Direct inoculation (ie from surgery, trauma)

- Contiguous spread

Presentation

- Back pain is most sensitive, although may not have point tenderness. Severe point tenderness may suggest an abscess.

- Fever often not present (50-60%)...may also be because of use of analgesics/antipyretics

Micro

- Bacterial: Staph Aureus, E. coli, Salmonella (e.g asplenic patients at risk of encapsulated organisms), and others, all have a 'tropism' for bone. In men with GU infection, gram negatives are often implicated as the bladder venous plexus drains to the level of the spine. CNST and P.acnes should be considered if prosthetic/fixation devices present.

- Mycobacterial ie TB Pott's disease

- Fungal infections specifically dimorphic fungi

MRSA risk factors include: homeless, incarceration, previous MRSA, contact sports, hospitalization

Principles of management 

- Get micro either from blood or biopsy or abscess drain if needed.

- Unless patient is unstable, try to hold off on antibiotics until a bug is identified.

- Duration varies, but often will be 6 weeks

- Clinical follow up is required. CRP, MRI may be useful in the right context. 

Click here for a great review from the NEJM (The above image is from this NEJM article by Zimmerli W. N Engl J Med 2010;362:1022-1029).