Premi®Test sample pre-treatment procedure for poultry- and pig-feed

Background

Using animal feed in a microbial inhibition test may result in false positive results due to the presence of several inhibitors in the raw materials of feed. To prevent these inhibitors interfering with the test result a special protocol is required to use the Premi®Test for the detection of antibiotic residues in poultry- and pig-feed.
DSM has developed a proprietary technology. This patented technology is described in this technical bulletin. Inactivating the proteinaceous factors through a new sample pre-treatment of the poultry- and pig-feed can prevent the influence of naturally

1. Sample preparation method

1. Wash hands before use and make sure to use a clean working surface.
2. Grind the feed in a mortar.
3. Take 10 gram of the grinded feed.
4. Add 30 ml of water.
5. Stir for half an hour at room temperature.

2. Instructions for using Premi®Test

1. Remove the aluminum foil carefully from the ampoule(s).
2. Use a clean tip on the syringe for each sample.
3. Cut of a small part of the tip-end.
4. Transfer 100 μl of the suspension onto the agar in the ampoule(s), by pressing the syringe once and releasing it. It will automatically take up the required volume.
5. Close the ampoule(s) with the plastic foil supplied with the kit.
6. Check temperature of the 2-step Incubator: 64°C (± 0,5 °C).
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7. Place the ampoule(s) in the Premi®Test 2-Step Incubator and push the “Start/Stop” button (see instructions).
8. The Premi®Test 2-Step Incubator automatically heats the samples for 10 minutes at 80°C.
9. After this heat pre-treatment, the Premi®Test 2-Step Incubator auto-matically incubates the samples at the required temperature of 64°C (± 0,5 °C).
10. Incubate the sample until the negative control changes color.
11. Use a negative sample (feed of the same origin without antibiotics) as control

Reading the test results

1. When the negative control changes color from purple to yellow, the results can be red.
2. Read the results from the bottom 2/3 part of the ampoule.
3. A clear color change purple to yellow indicates that the antimicrobial compounds are below the Premi®Test detection limits.
4. A purple color  indicates the presence of antibacterial substances at or above the detection limits of the Premi®Test.