The EN 17126 is a phase 2 step 1 suspension test. It is a sporicidal method that uses bacterial spores so it different from other suspension testing. The EN 17126 is for the medical and healthcare industry and when tested using Clostridium difficile is very relevant to reduce hospital required infections. The EN 17126 isn’t a mandatory test so you will only need it on your product if you are making a sporicidal or a clostridium claim. The other suspension testing for sporicidal activity is the EN 13704 but that is usually considered a little easier to pass. This is due to the fact in the EN 17126 spores are made in a way that ensures they are very hardy so can be difficult to kill. The spores are hardy anyway, so this just exaggerates the difficulty to get rid of them.
The EN 17126 is a suspension test which means it is carried out in a suspension of test organism, interfering substance and test product. The interfering substance and the organism make up 20% of this mix so even ready to use product are diluted to 80% during the testing. If the product is prediluted before the testing starts, we increase the percentage of product by 1.25 to account for the 80% dilution. In the EN 13624 there is a clause that states you can have a modified test that uses a ready to use product at 97% rather than the usual 80%. This is done by concentrating up the inoculum and interfering substance.
The EN 17126 only has two mandatory organisms which are the Bacillus subtills and the Bacillus cereus. If you just test against these two you can make a sporicidal claim. There is also the option in the standard to tested against Clostridium difficile in addition to the other two organisms. This will then mean you can claim against Clostridium. Often when selling into hospitals a Clostridium claim would be important as the number of hospital required infections caused by Clostridium difficile is going up and it can be hard to treat.
For BRP submission of a medical disinfectant the EN 13624 against Candida albicans is essential. As for all BPR submissions you must have three concentrations tested. These have to include the final usage concentration, a concentration that fails the test and then any other. Most commonly people opt for the end concentration, 50% of that and the 10% or 1% of that.
The table shows what the standard states as the test parameters but often the NHS will insist on different conditions. This could be 30 second contact time or dirty conditions even when the standards state oterhwise. If you are testing for a specific tender, you should check the requirements of this before testing.