A 35-year-old intravenous drug user presents with lower back pain, fever, and elevated CRP. MRI shows high T2 signal in the L3-L4 disc with endplate erosion and a pre-vertebral soft tissue collection. The most likely organism and the drug of choice pending culture are:

• A Staphylococcus aureus (including MRSA); vancomycin plus drainage ✓
• B Mycobacterium tuberculosis; rifampicin-based anti-tubercular therapy
• C Pseudomonas aeruginosa; piperacillin-tazobactam
• D Salmonella species; ciprofloxacin

Explanation

Hematogenous pyogenic vertebral osteomyelitis/spondylodiscitis in an IVDU is most commonly caused by Staphylococcus aureus, with a high rate of MRSA in the IVDU population. MRI is the gold standard for diagnosis showing T2 hyperintensity in the disc and adjacent endplates. Empirical vancomycin (MRSA coverage) is initiated pending blood cultures and CT-guided percutaneous disc biopsy results. TB spondylitis (Pott's disease) typically spares the disc initially, causes vertebral body collapse, and is endemic but less acute in presentation; it would have a subacute/chronic course.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.