Infections (+ TB)

Aetiology

Risk factors:

1. older debilitated patients

2. IV drug addicts (pseudomonas)

3. history of pneumonia, UTI, skin infection

4. immunocompromised patient

• 70% arise from UTI, chronically ill, elderly adults. Due to Batson's venous plexus = communication betw. pelvic & vertebral plexus.(NB surgically)

Organisms:

• Staph aureus is most common but MRSA is on the increase

• Gram negatives (E coli, Pseudomonas, Proteus) & anaerobes are on the increase

• Strep viridans

• brucellae, candidae, coccidiomycosis (in immunocompromised)

• tuberculosis (commonest site = T10)

Site of infection:

• lumbar spine is the area most often affected - uncommonly cause paralysis

• thoracic & cervical regions are affected less often but have a higher incidence of paralysis

Pathophysiology

• Haematogenous spread most common (Batson's complex)

• Organisms settle in the in metaphyseal region of vertebral body

• toxins cause thrombosis, infarct, abscess, blocks nutrition

• Purulent material may break out of cortex anteriorly to form paravertebral abscess or posteriorly to form an epidural abscess.

• weakening of the bone may cause vertebral collapse.