Quantitative surface test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in veterinary area on porous surfaces without mechanical action.
EN 16437 is a phase 2 step 2 carrier test for surface disinfectants intended for use in the veterinary area. The test evaluates the efficacy of the product against bacteria on porous surfaces.
The standard refers to the parameters to be observed when testing products for non-porous surface disinfection without mechanical action. This includes the test microorganism, test temperature, carrier, contact time and interfering substance.
- Test microorganism refers to the mandatory list of microbes that must be used in the test to determine the antimicrobial activity of the product. The mandatory microorganisms are assumed to represent all microbes in its group.
- Test temperature refers to the temperature in which the test must be conducted. The general assumption is that disinfectants are less effective in low temperatures compared to higher temperatures.
- Carrier refers to the material used in the test to simulate a contaminated instrument in the medical area. This test uses poplar wood as a carrier.
- Contact time refers to the minimum duration a product must remain in contact with the microbes for the product to be effective.
- Interfering substance refers to substance used in the test to simulate the possible contaminants that co-occur with microbes in the actual environment.
Refer to the table below for the minimum and additional test conditions.
In this carrier test, the test microorganism is added to the interfering substance and incubated for 2 minutes. 0.1ml of the microbial test suspension is applied to the poplar wood in a sterile petri dish and dried at 37°C. The poplar wood represents an actual porous surface.
The test surface is transferred into a petri dish containing test product solution. The surface must be completely submerged for 1 minute. The test surface is then transferred into a new sterile petri dish and placed on its edge against the side of the dish. The test surface is incubated for the specific contact time.
The test surface is transferred into a separate vessel containing TSB with neutralizer. The mixture is vortexed for 15 seconds and placed in a water bath at 20°C for 25 minutes. The vessels are placed in an ultrasonic bath with ice next and treated with ultrasound for 5 minutes to remove the bacterial cells from the test surface. The neutralizer solution is then acquired, diluted and plated.
The number of test microorganism recovered is compared to the microorganism recovered from the control sample (where test microorganism is exposed to water instead of disinfectant) to determine if the test product is effective.
Log reduction refers to the extent to which a product is capable of reducing the number of microbes. For example, 4-log reduction means the number of microorganisms on a surface has been reduced by 10 000 times. A product that is 99.9% effective against a certain microbe is said to have achieved 3-log reduction against that microbe.
For a product to pass EN 16437, it must be able to achieve 4-log reduction against the respective test microorganisms listed in Table 1 for bactericidal activity. In other words, the product must be able to kill 99.99% bacteria while meeting all the other requirements of the European standard.