## Chemical Sterilisation of TB-Contaminated Instruments **Key Point:** Glutaraldehyde 2% is the preferred chemical sterilant for instruments contaminated with Mycobacterium tuberculosis because it combines sporicidal activity with mycobactericidal potency and is widely available in hospital settings. ### Why Mycobacterium tuberculosis Requires Special Consideration 1. **Acid-fast bacilli** have a waxy mycolic acid cell wall resistant to many disinfectants 2. **Sporicidal activity** is essential because TB can form spore-like structures under stress 3. **Biofilm formation** on instruments necessitates a disinfectant with penetrating capacity ### Chemical Sterilants: Comparative Analysis | Agent | Sporicidal | Mycobactericidal | Contact Time | Clinical Use | Limitations | |---|---|---|---|---|---| | **Glutaraldehyde 2%** | Yes | Yes | 3–10 hrs | High-level disinfection/sterilisation | Toxic fumes, irritant | | Formaldehyde 4% | Yes | Yes | 6–18 hrs | Sterilisation (rarely used now) | Highly toxic, carcinogenic | | Hydrogen peroxide 6% | Weak | Yes | Minutes–hours | Intermediate disinfection | Poor penetration, unstable | | Ethylene oxide gas | Yes | Yes | 12–24 hrs | Industrial sterilisation | Requires special equipment, toxic | **High-Yield:** Glutaraldehyde is the **gold standard** for TB-contaminated instruments because: - Proven mycobactericidal activity against M. tuberculosis - Sporicidal at 2% concentration - Achieves sterilisation (not just disinfection) with extended contact - Suitable for hospital-based chemical sterilisation **Clinical Pearl:** In India, glutaraldehyde is the most commonly used chemical sterilant in operating theatres and TB wards for reusable instruments. It is cost-effective and does not require specialised equipment like ethylene oxide chambers. **Mnemonic:** **GAF** for chemical sterilants — **G**lutaraldehyde, **A**cetaldehyde, **F**ormaldehyde (older agents; formaldehyde is now avoided due to toxicity). **Warning:** Formaldehyde, though sporicidal and mycobactericidal, is a known carcinogen and is no longer recommended for routine hospital use. Ethylene oxide requires industrial-grade equipment and is not practical for routine instrument sterilisation in most Indian hospitals.
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