MI5.{2,5} | Bone & Joint Infections and Leprosy — Summary & Reflection

REFLECT

A 35-year-old woman from Chhattisgarh is diagnosed with multibacillary leprosy (BI 4+). She is embarrassed and refuses treatment, worried about stigma from her village. Her 12-year-old son lives at home with her. What are the public health implications of her decision? What specimens would you collect before starting MDT, and what microbiological parameters would you monitor during treatment? How does the BI change differently from the MI during effective therapy — and why does this matter for declaring 'cure'?

KEY TAKEAWAYS

Key takeaways from this SDL:

1. Osteomyelitis: Haematogenous → metaphysis (children) or vertebrae (adults); S. aureus is #1; Salmonella in sickle cell disease; sequestrum (dead bone) + involucrum (new bone) = chronic osteomyelitis.
2. Septic arthritis: Joint aspiration mandatory; WBC >50,000 with >75% PMNs = treat as septic; N. gonorrhoeae most common in young adults; cartilage destructs within hours.
3. Pott's spine: M. tuberculosis in vertebral bodies; gibbus deformity + cord compression — always think TB in endemic India.
4. Leprosy — spectrum: Tuberculoid (strong Th1, paucibacillary, well-formed granulomas) ↔ Lepromatous (weak Th1, multibacillary, foam cells, Grenz zone).
5. Slit-skin smear: Pinch, slit, scrape, spread; ZN stain; BI grades 1+–6+; Bacteriological Index for load, Morphological Index for viability.
6. Nerve damage: Superficial peripheral nerves (ulnar, median, common peroneal, posterior tibial, radial, facial, great auricular) — claw hand, foot drop, wrist drop, plantar anaesthesia.
7. MDT: PB = rifampicin + dapsone × 6 months; MB = + clofazimine × 12 months; free in India; BCG gives 60–80% protection.
8. Leprosy reactions: Type 1 (reversal) = CMI flare → prednisolone; Type 2 (ENL) = immune complex → clofazimine/thalidomide.