This International Standard gives general instructions for carrying out microbiological examinations in accordance with specific standards. The purpose of this International Standard is to help to ensure the validity of the examinations, to ascertain that the general techniques used for conducting these examinations are the same in all laboratories, to help achieve homogeneous results in different laboratories, and to contribute towards the protection of the health of the laboratory personnel by preventing risks of infection. This International Standard may be used wholly or partly for the accreditation of a laboratory by national organizations.