Miljøprojekt 1071/2006 – Evaluering af substratkontrol på de akkrediterede miljølaboratorier

Evaluering af substratkontrol på de akkrediterede miljølaboratorier

Summary and conclusions

The aim of this project was to set minimum demands for quality control of microbiological media in order to secure uniformity between the laboratories.

Questionnaires were sent to the laboratories and the answers were evaluated with respect to extent and level of quality control of media. Nine laboratories participated in the study. This report systematically evaluates both types of media as well as the specific medias and recommendations are given concerning frequency and type of quality control method.

It is recommended to control media batch wise when the laboratory it self prepare the media from basic ingredients. If commercial manufactured media are used it is recommended to control each supplied batch of media.

Quality control of dilution fluids is recommended to include composition, volume, pH, and sterility. Non-selective media are also recommended checked by qualitative or semi-quantitative methods, while selective media should be checked by quantitative methods.

When checking by qualitative and quantitative methods it is recommended to use relevant positive and negative test strains in appropriate concentrations.