Did you Know?
In infection control, a biological indicator (BI) is the final verification step to assess the effectiveness of a sterilization cycle. Even if the autoclave operates perfectly, only proper handling of the biological indicator ensures accurate results reflecting sterilization effectiveness.
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Key points to remember when using biological indicators:
1️⃣ Incubate immediately after activation
Once activated, the BI tube should be placed in the incubator immediately. Delays can cause the reaction between spores and the culture medium to reach equilibrium—fluorescence signals may stop increasing, leading to false-negative results (the signal is actually positive but reads negative, even for the control tube).
2️⃣ Ensure the ampule fully breaks during activation
Make sure the internal ampule is completely broken so the culture solution spreads evenly over the spore strip. If not fully broken, spores will not contact the medium, producing incorrect (false-negative) results, even when the control tube reads negative.
3️⃣ Do not re-incubate or re-read the BI
Biological indicators are designed for one-time incubation and reading only. Re-incubating or re-reading later is meaningless and can lead to misinterpretation of sterilization effectiveness.
💡 Each biological indicator is a highly sensitive test. Following the correct procedure ensures accurate results and contributes to patient safety, the highest priority in infection control.
📋 Standards and regulations:
Using BIs must comply with professional standards. According to the Vietnam Ministry of Health (Decision No. 3671/QĐ-BYT, Sept 27, 2012) and ANSI/AAMI ST79:2017, the following rules apply:
🔹 1. Mandatory use of BIs for loads containing implantable devices.
🔹 2. For loads without implants, minimum weekly testing is required; daily testing is recommended.
🔹 3. Required for sterilizers with volume > 56.6 liters (2 ft³).
🔹 4. Always use a control tube from the same lot as the test tube to cross-check sterilizer performance and reader accuracy.
💡 Following these procedures not only ensures regulatory compliance but also protects patients and increases the reliability of the entire infection control system.
Content Responsibility: Dr. Pham Thi Thanh Thuy
📌 For more information, contact hotline: 093 955 66 66 or 084 880 1708