Nucleic acid amplification controls

A method for detection of a microorganism in a biological test sample comprising:

• a) providing a biological fluid test sample suspected of comprising the microorganism;
• b) providing a positive control sample comprising the microorganism in a biological fluid corresponding to the biological fluid of the test sample, wherein the positive control sample is prepared by exposing a purified microorganism to an aldehyde such that the microorganism is in an intact, non-pathogenic, form in which one or more of the surface proteins have been irreversibly modified by covalent attachment to the aldehyde and wherein the nuclear components are substantially intact;
• c) processing the test and the positive control sample to extract the nuclear components of the microorganisms;
• d) amplifying the nuclear components of the microorganisms in the test sample and the positive control;
• and
• e) comparing the results of nucleic acid amplification in the test sample and the positive control to identify the presence of microorganisms in the test sample.