Microbiological immersion challenge tests

A rigorous approach to microbiological immersion challenge testing is depicted in Fig. 1. This method uses Pseudomonas diminuta grown in Lactose Broth at 3 rc for 24 h. The culture is then sonicated before use to break up any microcolonies or rosettes that may have arisen and that may reduce the potential for this microorganism to penetrate across tiny flaws in intended microbial barriers. 

Microbiological approaches such as that described above are very evidently laborious, time-consuming, and unsuited to routine use. Dye penetration may be substituted for microbiological immersion challenge testing in routine use. 

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