Introduction to Listeria Monocytogenes Detection
📌 The training session focuses on demonstrating the detection testing for Listeria monocytogenes in food using a GLISA (Gold Labeled Immunosorbent Assay) rapid test.
🦠 Listeria monocytogenes is a Gram-positive, rod-shaped bacterium that serves as an indicator of food safety and its presence in food/beverages is not permissible.
🔬 The testing principle relies on immunochromatography utilizing gold-labeled antibodies for rapid detection, adhering to validated international reference methods.

Testing Procedure and Sample Preparation
🧪 The process begins by preparing necessary materials, including the appropriate analysis method instruction, solvents like Half Fraser Broth and Fraser Broth, and the microbial reference standard (Listeria monocytogenes ATCC 7644).
🥣 Sample preparation involves weighing 25 grams of the sample into a sterile container, adding 225 mL of Half Fraser Broth, and homogenizing to achieve a $10^{-1}$ dilution.
🌡️ The primary enrichment step requires incubation at 28–30°C or 35–37°C for 21–24 hours.
🔄 A secondary enrichment involves inoculating 0.1 mL of the primary enrichment into 10 mL of Fraser Broth and incubating under the same temperature conditions for another 21–24 hours.

Rapid Test Application and Interpretation
💧 For the rapid test, 150 µL of the unheated or heat-treated/cooled enrichment is dispensed onto the circular sample port of the single-pad test device using a micropipette.
⏱️ The test device must be incubated at room temperature, and results should be observed after 30 minutes.
✅ A valid and positive result is indicated by the formation of a red line in both the Test zone (T) and the Control zone (C).
❌ A valid and negative result shows a red line only in the Control zone (C).

Key Points & Insights
➡️ If the control line (C) does not appear, the test is invalid and must be repeated.
➡️ If the result is negative, it can be reported directly, but a positive result requires confirmatory testing following the referenced analysis method.
➡️ Maintaining sterile equipment and calibrated measuring tools is crucial for ensuring test validity during preparation.

📸 Video summarized with SummaryTube.com on Dec 01, 2025, 04:02 UTC