Specialty Fabrics Review December 2019 - 51

generally tested for efficacy against bacteria,
so references about health-care textile testing
will be concerning antibacterial properties
and will limit testing options only to testing
antibacterial chemistries.
Testing laboratories have several means to
test antibacterial textiles. In the United States,
the American Association of Textile Chemists
and Colorists (AATCC) and American
Society for Testing and Materials (ASTM)
have developed antibacterial textile tests.
Internationally, there are several additional
tests available.
The tests do a great job at describing the
capacity of an antibacterial textile to either
prevent bacterial growth or kill the specified
bacteria. These methods are excellent for
refining the antibacterial formulation in
a textile product during development and
for determining the quality of antibacterial
application during production. However,
they fall short in determining efficacy on
bacteria in the real world.
CURRENT METHODS
While each of the established test methods
serves an important role in the development
of effective antibacterial textiles, they are
inadequate with regards to the medical
community, largely due to the conditions
of the methods. With the exception ASTM E
2149, each of these tests has a 24-hour contact
time between a liquid bacterial inoculum and
the treated textile.
Essentially, the textile is kept in a humid
chamber with the bacteria. While humid
conditions are critical for the bacteria (they
will die in a dry environment) and a 24-hour
period is needed to see adequate growth of
the bacteria on an untreated textile, these
conditions do not represent real life for a
medical textile, such as a typical scrub suit
(unless it's at the bottom of a hamper).
With ASTM E 2149, the testing conditions
are even more convoluted. Because this method
was developed for hydrophobic textiles, like
those treated with quaternary silanes, the
liquid bacterial inoculum must be in constant
and vigorous contact with a treated textile.
Therefore, a greater inoculum volume is used
and the system is shaken over the course of an
hour using a wrist-action shaker-something
clothing will not likely experience in the course

HEALTH-CARE TEXTILES ARE AT THE
FRONT LINE OF THIS WAR AGAINST
INFECTED BODY FLUIDS AND THE
SPREAD OF DISEASE.

of a day. But it was intended as a fast quality
assurance test method.
Indeed, there is still controversy with
regards to clinical evidence for antibacterial
efficacy of treated textiles. The lack of a solid
connection between laboratory data and
clinical performance may be due to the nature
of the test methods described. Clinical trials,
much like field wear trials, are complicated
tasks involving many people, and so can be
very expensive and time consuming.
WHAT IS NEEDED
The industry needs test methods that bridge the
gap between the basic test methods currently
available and arduous and expensive clinical
trials. The Expert Group on Efficacy of Biocide
Treated Articles within the Organization for
Economic Cooperation and Development,
Task Force on Biocides recommends a threetiered approach to determining efficacy of
antibacterial treated articles.
*Tier 1: Proof of Principle defines the basic
industry standard tests that determine
efficacy of an antibacterial treated article
in a controlled laboratory environment.
*Tier 2: Simulated Use defines the translational tests that mimic end-use scenarios,
environments and incubation times.
*Tier 3: In-Use Evaluation substantiates
direct health benefit claims or supports
marketing initiatives by the development
of clinical trials that take place in end-use
environments under real-world conditions.
The current standard test methods fit the
Tier 1 category. Clearly, clinical trials fall
into Tier 3 testing. What's missing are Tier
2 test methods for medical textiles. These
should be laboratory-based and predictive
of eventual clinical trials. Such an approach
will, in the end, save the industry considerable
time and money.
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