ISO 17721-1:2021

Overview

ISO 17721-1:2021 specifies quantitative test methods for evaluating the antibacterial activity of glazed and unglazed ceramic tile surfaces that have incorporated antibacterial agents. The standard defines how to prepare, inoculate, incubate and recover test organisms and how to calculate antibacterial activity (expressed as the log difference between treated tiles and untreated controls). It clarifies that secondary effects of antibacterial treatments (chemical resistance, stain resistance, small colour differences) are outside its scope and refers to ISO 10545‑13, ISO 10545‑14 and ISO 10545‑16 for those topics. Results are tied to the experimental conditions used and do not automatically predict performance under different environmental or biological conditions.

Key topics and technical requirements

• Test organisms: Method developed for Escherichia coli and Staphylococcus aureus (specified culture collections); other species can be tested if reported.
• Materials and media: Detailed preparation of culture media and solutions (nutrient broth/1/500 nutrient broth, nutrient agar, SCDLP, PBS) and use of non‑ionic surfactant (polysorbate 80).
• Test specimen: Typical specimen size ~50 × 50 mm (±2 mm) or alternative sizes that permit coverage by a defined film area; all surfaces must be sterilized prior to testing.
• Procedure steps: Preparation of inoculum, application using an adhesive film, inoculation, incubation, recovery of bacteria at t = 0 and post‑incubation, and enumeration of viable counts.
• Validation and calculations: Criteria for a valid test, procedures for recovery efficiency, and calculation of antibacterial activity as the logarithmic reduction relative to untreated controls.
• Laboratory safety: Handling of microorganisms requires trained personnel and appropriate biosafety practices.

Applications and users

Practical uses of ISO 17721‑1 include:

• Product development and quality control for ceramic tile manufacturers incorporating antibacterial agents.
• Third‑party and in‑house laboratory testing to substantiate performance claims.
• Procurement and specification by architects, healthcare facility managers, and designers seeking tiles with documented antibacterial properties.
• Regulatory bodies and certification schemes requiring standardized comparative data.

Who uses it: tile producers, independent test laboratories, R&D teams, compliance officers, specifiers, and purchasers in healthcare and public spaces.

Related standards

• ISO 10545‑13 - Chemical resistance of ceramic tiles
• ISO 10545‑14 - Stain resistance of ceramic tiles
• ISO 10545‑16 - Assessment of colour differences
• ISO 17721 series - other parts addressing different tile surface treatments (see ISO website for the series list)

Keywords: ISO 17721‑1, antibacterial activity, ceramic tile surfaces, test methods, E. coli, S. aureus, nutrient broth, SCDLP, PBS, validation, log reduction.