Here - PFI Group
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KBE<br />
1,0E+08<br />
1,0E+07<br />
1,0E+06<br />
1,0E+05<br />
1,0E+04<br />
1,0E+03<br />
1,0E+02<br />
1,0E+01<br />
1,0E+00<br />
34<br />
Newsletter<br />
MICRoBIoLoGY<br />
Changes to ASTM E2149 / Challenge Test Method<br />
Test Method for Antibacterial<br />
Activity Updated<br />
Incubation of the culture medium plates<br />
Example of a material showing antibacterial<br />
activity towards Klebsiella pneumoniae<br />
0h<br />
1h<br />
5,0E+05<br />
2h<br />
6,9E+04<br />
3h<br />
3,3E+06<br />
4h<br />
5h<br />
6h<br />
7h<br />
8h<br />
9h<br />
10h<br />
11h<br />
12h<br />
13h<br />
Time<br />
14h<br />
15h<br />
16h<br />
17h<br />
Antibacterial Activity Can Also<br />
Be Expressed in “Log Steps”<br />
According to the updated version of the test method,<br />
the antibacterial activity can be stated, as desired, either<br />
as a percentage reduction of microbial count or as<br />
the difference of the decadic logarithms, known colloquially<br />
as ‘log steps’. These are just two different ways<br />
of expressing the laboratory values determined.<br />
Depending upon the material, the antibacterial agent,<br />
and the field of application, differing requirements<br />
have to be satisfied which need to be agreed between<br />
the contracting parties. The above standard method is<br />
used to determine antibacterial activity, not to evaluate<br />
the results.<br />
A test for antibacterial efficacy should always include<br />
independent testing towards a gram-positive and a<br />
gram-negative bacterium, because the two differ in<br />
their cell structure. Antibacterial efficacy is assured<br />
only if there is activity against both groups of bacteria.<br />
18h<br />
19h<br />
20h<br />
21h<br />
22h<br />
23h<br />
4,2E+07<br />
24h 1,0E+00<br />
Material<br />
Control
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