Microsart^® Validation Standards are not infectious and therefore safe in use. They are titrated to 99 CFU/ml, the sensitivity limit for sterility tests according to European Pharmacopoeia (EP) 2.6.1 Sterility. The bacteria strains used for the manufacture of Microsart® Validation Standard are low passage reference strains cultivated in suitable culture broth. The cultures are harvested in the early logarithmic phase of the growth to avoid an atypical high ratio of dead bacteria and plated on Agar medium for quantification based on Colony-forming Units (CFU).