Antimicrobial Activity of New Carpets according to AATCC 174: 2022

aatcc174
Testing lab
Microbiology
Legislation
Contruction Products Regulation (EU) 305/2011
Testing standard

AATCC 174: 2022

Principle

The main purpose of AATCC 174:2022 – Antimicrobial Activity Assessment of Carpets is to:

  • Determine the efficacy of antimicrobial agents incorporated into or applied onto new carpets.
  • Evaluate a carpet’s resistance to microbial growth.
  • Compare the performance of antimicrobial-treated carpets to untreated ones.
  • Aid manufacturers in quality control and product development.

Three test methods are used:

Qualitative Assessment (Agar Plate Method)

Purpose: To observe zones of inhibition indicating antimicrobial activity.

Procedure:

  • Carpet specimens are placed onto agar plates inoculated with bacteria or fungi.
  • After incubation (usually 24-48 hours), the area around the specimen is examined for zones where microbial growth is inhibited.

Result: Qualitative; based on presence and size of clear zones around the carpet.

Quantitative Assessment (Shake Flask Method)

Purpose: To quantitatively determine the reduction in microbial populations.

Procedure:

  • Carpet specimens are placed in a flask with a microbial suspension and shaken for a defined time.
  • The microbial count is determined before and after exposure using colony-forming unit (CFU) counts.

Result: Quantitative; expressed as a log reduction in microbial population.

Fungal Resistance (Mil-Std 810-type Test)

Purpose: To evaluate fungal growth on carpet materials under high humidity.

Procedure:

  • Carpet samples are inoculated with fungi and incubated under warm, humid conditions (typically 28–30°C at ≥95% relative humidity).
  • Growth is rated visually based on a standard scale (e.g., 0–4).

Result: Qualitative to semi-quantitative; evaluates extent of fungal colonization.

Test microorganisms

  • Bacteria: Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli.
  • Fungi: Aspergillus niger, Penicillium spp., Chaetomium globosum.

Applications

  • Used by carpet manufacturers and product developers.
  • Relevant for certification, marketing claims, and regulatory compliance.
  • Supports decisions about antimicrobial treatment durability and efficacy.

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