AATCC Test Method 147 – Antibacterial Activity of Textile Materials: Parallel Streak

AATCC Test Method 147 is a qualitative test method that is used to assess the antibacterial activity of treated textile material.  The method provides an overview of antibacterial activity by looking at the growth of the bacteria, which decreases from one end of each streak to the other and from one streak to the next, resulting in reduced sensitivity.  The size of the zone of inhibition and the narrowing of the streaks caused by the presence of the antibacterial agent permit an estimate of the residual antibacterial activity after multiple washings.

Why This Assessment is Performed

AATCC 147 is performed to assess the bacteriostatic properties of textile materials. This method is simple and provides a visual representation of antibacterial activity in the test sample. The method is not suitable for materials which tend to encapsulate and prevent the diffusion of the antibacterial agent or contain antibacterial-neutralizing substances.
Test Organisms: Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352
Test Specimen: Non-sterile, treated and untreated samples (same as test material minus the antibacterial agent).

Have you tried our Test Navigator Tool? Try it now

Steps in Conducting This Test

1. Test Sample Preparation: Rectangular swatches of the test and control samples are cut to specified dimensions.
2. Test Organism Preparation: The test organisms are prepared by thoroughly mixing an appropriate volume (1:10) of a 24-hour culture and sterile water. Using a sterile inoculating loop, one loopful of the diluted culture is transferred onto a pre-poured Petri plate containing the appropriate media by making five (5) parallel streaks without refilling the loop.
3. Test Sample Placement: Precut rectangular swatches of the test specimen are gently placed/pressed transversely across the five inoculum streaks to provide good contact with the agar surface.
4. Incubation: Inoculated plates containing the test specimen are then incubated at 37°C for 21±3 hours.
5. Antibacterial Activity Assessment: After incubation, the plates are removed from the incubator and examined for an interruption of growth along the streaks of inoculum beneath the test sample and a clear zone of inhibition around the sample. Inhibition undth the test specimen and the zone of inhibition around the sample demonstrate antibacterial properties.

Standards, Guidance, and Regulations

• AATCC Test Method 147: The primary standard for assessing antibacterial activity in textiles.