INF ECT ION PR EVENT ION & CONT ROL
testing against. This depends on how the product is intended to be used. For example, EN 17126:2018 relates to disinfectants claiming sporicidal activity, which might not always be required. Whereas EN 14476:2013+A2:2019 which relates to virucidal activity should always be considered when efficacy against viruses including coronaviruses is of paramount importance. l EN 13624:2013 “Chemical disinfectants and antiseptics. Quantitative suspension test for the evaluation of fungicidal or yeasticidal activity in the medical area. Test method and requirements (phase 2, step 1)”. This supersedes EN 13624:2003
l EN 13727:2012+A2:2015 “Chemical disinfectants and antiseptics. Quantitative suspension test for the evaluation of bactericidal activity in the medical area. Test method and requirements (phase 2, step 1)”. This supersedes EN 13727:2003
l EN 14476:2013+A2:2019 Chemical disinfectants and antiseptics “Quantitative suspension test for the evaluation of virucidal activity in the medical area - Test method and requirements (Phase 2/Step 1)”.
l EN 17126:2018 “Chemical disinfectants and antiseptics. Quantitative suspension test for the evaluation of sporicidal activity of chemical disinfectants in the medical area. Test method and requirements (phase 2, step 1).”
These European Standards apply to products that are used in the medical area in the fields of hygienic hand rub, hygienic handwash, surgical hand rub, surgical handwash, instrument disinfection by immersion, and surface disinfection by wiping, spraying,
As standards become increasingly rigorous, to protect both patients and staff, there appears to be little incentive for disinfectant manufacturers to test to newer, tougher standards, which could mean increased disinfectant concentration times and longer contact times, to ensure microbial efficacy.
flooding or other means. They apply to areas and situations where disinfection or antisepsis is medically indicated. The standards outlined above evaluate disinfectants through the suspension test for instrument disinfection by immersion, and surface disinfection by wiping, spraying, flooding or other means. The basic requirement is at least a 5-log reduction of vegetative microbial cells under EN 13624 and EN 13727 and a 4-log reduction for bacterial spores under EN 17126 (which are harder to kill).
The suspension test to evaluate disinfectant efficacy
The disinfectant efficacy validation aims to provide documented evidence that the disinfectant demonstrates the virucidal, bactericidal, fungicidal, and/or sporicidal activity necessary to control microbial contamination in general and to eliminate pathogens of concern.
The purpose of the quantitative suspension test, as set out in the above standards, is to evaluate the activity of a given disinfectant against a range of
microorganisms under conditions that closely simulate the practical use of the disinfectant. The test consists of inoculating a prepared sample of the disinfectant under test in simulated ‘clean’ and ‘dirty’ conditions using a challenge suspension of the test microorganism.2
After a specified
contact time an aliquot is removed, and the microbicidal action is immediately neutralised by the addition of a proven neutraliser. Without an effective neutralising agent, the disinfectant may continue to have an inhibitory effect on the test samples during recovery testing, leading to inaccurate results. Selection of the appropriate neutralising agent is dependent upon the nature of the disinfectant. Following this neutralisation step, the number of surviving microorganisms in each sample is determined through the counting of agar plates and the reduction in viable microorganisms is calculated.3
Suspension tests require the disinfectant to be of a certain concentration and to be evaluated for a controlled period of time. This assesses how the disinfectant is presented in practice and for how long it needs to be applied. In addition, the disinfectant is made up in the ‘worst case’ condition by using ‘water of standard hardness’ (which contains ions like magnesium and calcium, as well as other salts). A further condition is the simulation of ‘soiling’ (the ‘dirty’ conditions mentioned above), which is achieved by the addition of bovine serum albumin (at 0.03%, representing ‘clean’ conditions and at 0.3% representing ‘dirty’ conditions.4 To demonstrate the effectiveness of a disinfectant, the product must be challenged using a panel of microorganisms that are reflective of the clinical setting. The appropriate organisms are set out in the standards, although with the EN 17126:2018 test, the biocidal activity of the disinfectant should be taken into account when selecting the panel of organisms (in the clinical setting, Clostridium difficile is an appropriate bacterium to select). This means the EN 17126: 2018 is only applied to disinfectants labelled as sporicidal. When it comes to the selected disinfectant,
36 l
WWW.CLINICALSERVICESJOURNAL.COM OCTOBER 2020
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92
