ISO 22196:2011

Overview

ISO 22196:2011 specifies a standardized laboratory method for measuring the antibacterial activity of antibacterial‑treated plastics and other non‑porous surfaces. The method (based on JIS Z 2801) evaluates how effectively a treated surface suppresses bacterial growth by comparing viable cell counts on treated vs. untreated specimens under controlled conditions. The standard is limited to antibacterial‑treated, non‑porous articles and is not intended to assess untreated surface colonization, biodegradability, textiles, building materials (except where used as treated articles), or photocatalytic materials.

Key technical topics and requirements

• Test organisms: Two bacterial species are mandatory - Staphylococcus aureus and Escherichia coli (commonly referenced strains include ATCC 6538P and ATCC 8739). Other species may be used if justified and reported.
• Measurement principle: Antibacterial activity is expressed as the difference in the logarithm of viable cell counts (log reduction) between antibacterial‑treated and untreated control surfaces after inoculation and incubation.
• Culture media & neutralizers: Specifies media such as 1/500 nutrient broth (1/500 NB), nutrient agar, plate count agar and the use of SCDLP broth (soybean casein digest broth with lecithin and polyoxyethylene sorbitan monooleate) as a neutralizer for many agents.
• Procedure elements: Covers pre‑culture, specimen preparation, inoculation, incubation, recovery of bacteria, and viable count determination (pour plate method).
• Validation & reporting: Defines conditions for a valid test, calculation of antibacterial activity, and includes guidance on repeatability, reproducibility and required test report content.
• Safety & competence: Warns that handling microorganisms requires trained personnel and adherence to microbiological practice and national regulations.

Practical applications and users

ISO 22196 is used for:

• Product R&D to screen and optimize antibacterial additives or surface treatments.
• Quality control and manufacturing lot verification for treated plastics, coatings, rubbers, stainless steel and other non‑porous consumer or industrial articles.
• Supporting product performance claims in technical documentation (with the caveat that results reflect only the specific test conditions). Primary users include materials scientists, microbiologists, product developers, quality managers, and independent testing laboratories that evaluate antibacterial surfaces.

Related standards

• ISO 846 - effects/propagation of bacteria on non‑porous surfaces (untreated)
• ISO 20743 - antibacterial activity for textile products
• ISO 27447 - assessment of photocatalytic materials
• ISO 7218 - general microbiological examination guidance
• JIS Z 2801 - original method on which ISO 22196 is based

Keywords: ISO 22196, antibacterial activity, plastics, non‑porous surfaces, S. aureus, E. coli, SCDLP, 1/500 NB, JIS Z 2801, antibacterial test method.