CLAUSEN MEDIUM

Clausen Medium was developed by Clausen. This medium is also called as HS-T (Dithionite Thioglycollate) Medium and is recommended for sterility testing by the Nordic Pharmacopoeia Board. Random sample selection is recognized by the Board and they refer to the process as microbial-contamination test. The Standard microbial contamination test is developed to establish the number of non-sterile units, if any in batch, is below a specific level. Random sampling in sufficient quantity of the bulk should be examined. In the microbial contamination test for detecting the non-sterile units, two methods can be used viz. Membrane filter method and Dilution method. The test must be performed with all precautions taken to prevent laboratory contamination.
This medium is clear in appearance and yellow coloured. Under aerobic conditions it turns pink. Therefore, at the time of use the upper one third of the medium should be pink. The standard microbial contamination test is passed if growth is not observed in any of the tubes. Growth is examined by the appearance of turbidity in fluid or semi fluid media and by the formation of colonies on solid media.

used as sterility medium as per Nordic Pharmacopoeia Board