Standard Guide for Evaluating Non-culture Microbiological Tests

Abstract

5.1 This guide should be used by producers and potential producers of non-culture tests to determine the accuracy, selectivity, specificity, and precision of the tests, as defined in Practice E691. Results of such studies should identify the limitations and indicate the utility or applicability of the non-culture test, or both, for use on different types of samples. Guide E1488 recommends other statistical tools for evaluating the suitability and applicability of proposed new test methods. 5.2 Non-culture test users and potential users should employ this guide to evaluate results of the non-culture test as compared to their present methods. Practices D5245 and D5465 should be reviewed in regards to the microbiological methods employed. If culture methods have not been used for monitoring the systems, then guidelines are included for obtaining microbiological expertise. 5.3 Utilization of a non-culture test can reduce the time required to determine the microbiological status of the system and detect microbe that are not detected by culture testing. Consequently, non-culture tests can contribute to the improvement in the overall operating efficiency of microbial contamination condition monitoring and diagnostic efforts, and microbicide performance evaluations. 5.4 Detecting microbial contamination levels that exceed predetermined upper control limits indicates the need for an addition of an antimicrobial agent or other corrective maintenance action. By accurately determining this in a shorter time period than is possible than by culture methods, treatment with antimicrobial agents may circumvent more serious problems than if the treatment were postponed until culture results were available. If the antimicrobial treatment program relied on an inaccurate non-culture test, then unnecessary loss of product and problems associated with inappropriate selection or improper dosing with antimicrobial agents would exist. 5.5 Since many methods based on entirely different chemical and microbiological principles are considered, it is not possible to establish a unique design and recommend a specific method of statistical analyses for the comparisons to be made. It is only possible to present guides that should be followed while performing the experiments. It is also recommended that a statistician be involved in the study.