Unusual biological behavior of staphylococci with nano silver assayed by microtiter-plate

The microtiter-plate test is the most frequently used techniques for quantifying biofilm formation, an important indicator for the pathogenicity of staphylococci. The purpose of the present study was to develop a microtiter-plate test, as a quantitative assay, for nano silver toxicicity. It is also superior to the standard microtiter-plate test because it enables indirect measuring of bacteria attached both to the bottom and to the walls of the wells in present of nano silver. It was surprising that 0.2 ppm of nano silver promote the formation of biofilm while above this concentration inhibit the biofilm formation by Staphylococcus.