Testing Hygienic Coatings and Surfaces
These methods evaluate the antibacterial activity of antibacterial-treated plastic products and other non-porous materials including paint films. The method can also be adapted for porous materials.
| Antimicrobial Activity ('wet' test: uses suspended inoculum) | ISO 22196 (formerly JIS Z 2801) |
| Antimicrobial Activity ('dry' test: uses non-suspended inoculum) | PRA test method |
Anti-Bacterial Activity: ISO 22196:2007
(formerly JIS Z 2801:2000)
Scope and Field of Application
This standard specifies a method of evaluating the antibacterial activity of antibacterial-treated plastic products and other non-porous materials including paint films.
A value for the antibacterial activity is determined but there is no pass/fail criterion defined in the standard. This is a matter of agreement between the parties concerned. (The earlier JIS standard specified a value of 2 or greater as demonstrating antimicrobial activity).
The actual standard is a copyright-protected document and we are not able to provide you with a copy. If required however, you can easily obtain one from the British Standards Institution.
Summary of Method
The standard describes the procedure used in which a bacterial suspension is applied to the test specimen and control pieces which are then incubated for 24 hours. Counts are determined before and after incubation. Using a formula provided in the standard, the log of the difference between the 2 counts is determined to give a measurement of antimicrobial activity. This can also be expressed as % kill.
The standard specifies the use of 2 bacterial species (Staphylococcus aureus and Escherichia coli) however we routinely carry out the test using other bacteria such as MRSA, Pseudomonas, Listeria, Salmonella, Bacillus, Acinebacter etc., as well as fungi such as Aspergillus and Candida.
The standard specifies an incubation period of 24 hours but other time periods can be accommodated.
Sample Requirements
We require either a 100 ml sample of paint or sufficient material which we can then cut to provide 6 samples, 50mmx 50mm, per organism to be tested.
Anti-Bacterial Activity: Non-Suspended Inoculum (NSI) Method
Scope and Field of Application
This test can be used to evaluate the antibacterial activity of antibacterial-treated plastic products and other non-porous materials including paint films. In the NSI method the bacteria are applied to the test specimens as a non-suspended inoculum (in contrast to ISO22196 where the inoculum is applied in an aqueous suspension). This is considered to be a more realistic approach for many coatings/ surfaces as the test conditions more closely resemble in-use conditions.
As with ISO22196 a value for the antibacterial activity is determined but there is no pass/ fail criterion. This is a matter of agreement between the parties concerned.
This work is not carried out to any international standard, we use our own in-house method.
Summary of Method
Using a non-suspended inoculum the test bacteria are applied to the test specimen and control pieces which are then incubated for 24 hours. Counts are determined before and after incubation. A formula is used to determine the log of the difference between the 2 counts to give a measurement of antimicrobial activity. This can also be expressed as % kill.
The test is normally carried out using Staphylococcus aureus and Escherichia coli as the test organisms, Other bacteria such as MRSA, Pseudomonas, Listeria, Salmonella, Bacillus, Acinebacter etc., as well as fungi such as Aspergillus and Candida, can be also be used but with these organisms some preliminary work is required.
An incubation period of 24 hours is normally used but other timescales can be accommodated.
Sample Requirements
We require either a 100 ml sample of paint or sufficient material which we can then cut to provide 12 samples, 50mmx 50mm, per organism to be tested.
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