Patient: 56-year-old hospital worker (nurse) Presentation: 4-week history of severe unremitting low back pain, low-grade fevers, unable to work Relevant history: Type 2 diabetes (poorly controlled, HbA1c 9.5%), recent urinary tract infection treated with oral antibiotics 6 weeks ago, no IVDU, no recent spinal procedures, no prior back surgery, no immunosuppression Examination findings:
| Test | Result | Normal Range | Interpretation |
|---|---|---|---|
| Hb | 103 g/L | 115-155 g/L | ↓ Anaemia of chronic disease |
| WCC | 14.5 ×10⁹/L | 4-11 ×10⁹/L | ↑ Leucocytosis |
| Platelets | 385 ×10⁹/L | 150-400 ×10⁹/L | Normal |
| CRP | 185 mg/L | <5 mg/L | ↑ Markedly elevated |
| ESR | 98 mm/hr | <20 mm/hr | ↑ Markedly elevated |
| Procalcitonin | 2.5 ng/mL | <0.5 ng/mL | ↑ Elevated (bacterial infection) |
| Albumin | 28 g/L | 35-50 g/L | ↓ Low |
| ALP | 145 U/L | 30-120 U/L | ↑ Mildly elevated |
| GGT | 85 U/L | <60 U/L | ↑ Elevated |
| HbA1c | 9.5% | <6.5% | ↑ Poor glycaemic control |
| Creatinine | 95 μmol/L | 45-90 μmol/L | ↑ Mildly elevated |
| Urine MCS | E. coli >100,000/mL | - | Active UTI |
| Blood cultures | Pending | - | Await results |
Image 1: Lumbar Spine X-ray (AP and Lateral)
Radiological features:
Image 2: MRI Lumbar Spine (T1, T2, STIR, Post-contrast)
Findings:
What is the diagnosis and what is the likely source?
What are the key differential diagnoses and how do you distinguish them?
What investigations would you request and why?
Describe your management plan.
What are the indications for surgical intervention?
What is the expected outcome and follow-up?
This pattern suggests Pyogenic Spondylodiscitis:
Differentiate from TB:
| Feature | Pyogenic | Tuberculous |
|---|---|---|
| Onset | Acute (weeks) | Insidious (months) |
| Fever | High-grade | Low-grade or absent |
| CRP | Very elevated | Mildly elevated |
| Skip lesions | Rare | Common (30%) |
| Kyphosis | Mild | Severe ("gibbus") |
| Response to treatment | Weeks | Months |
Q: "When would you consider echocardiography?"
Echocardiography indications in spinal infection:
| Indication | Reason |
|---|---|
| S. aureus bacteraemia | 10-15% have concurrent endocarditis |
| Multiple embolic sites | Suggests cardiac source |
| New murmur | Valvular vegetations |
| IVDU | High risk of right-sided endocarditis |
| Prosthetic valve | Very high risk |
| Persistent bacteraemia | Consider uncontrolled source |
For this patient: If blood cultures grow S. aureus → mandatory echo (TTE, consider TOE).
Q: "What is the role of bracing?"
Bracing in spinal infection:
| Indication | Type | Duration |
|---|---|---|
| Lumbar discitis | TLSO | 6-12 weeks |
| Thoracic | TLSO | 6-12 weeks |
| Cervical | Hard collar | 6-12 weeks |
Benefits:
Not a substitute for antibiotics or surgery when indicated.
Q: "What organisms would you consider in IVDU?"
Organisms in IV drug users:
| Organism | Frequency | Notes |
|---|---|---|
| S. aureus (MRSA) | Most common | Often MRSA |
| Pseudomonas | 10-15% | Cervical spine predilection |
| Candida | 5-10% | Consider in failed treatment |
| Polymicrobial | 10-20% | Multiple organisms |
Empirical therapy in IVDU: Vancomycin + anti-pseudomonal beta-lactam (e.g., ceftazidime)
Q: "How do you differentiate Modic type 1 changes from infection?"
Modic type 1 vs Infection:
| Feature | Modic 1 | Infection |
|---|---|---|
| Disc height | Preserved | Lost |
| Endplates | Intact | Eroded |
| Enhancement | Linear | Diffuse |
| Disc signal | Normal | Abnormal (high T2) |
| Clinical | Chronic pain | Fever, acute pain |
| Inflammatory markers | Normal | Elevated |
When in doubt, CT-guided biopsy is definitive.