According to ISO 16140:2003 at least three levels of contamination
should be tested. In this study, four levels were analysed (D-6 to D-9).
They were spiked on four different swabs. Four independent analyses
of these four swabs were performed for each tested bacteria. As the
ISO 16140:2003 requires at least six repetitions, the dilution identified
as relative detection level with each individual detection method was
re-analysed with six swabs.