INTERNAL QUALITY-CONTROL SAMPLES FOR WATER BACTERIOLOGY

A method is described for the preparation and application of a bacteriological quality control system for use with tests for plate counts and the enumeration of indicator organisms in water. Statistical limits are obtained and control charts prepared which are analagous to those used in analytical chemistry and clinical biochemistry laboratories. This approach has been applied successfully in this laboratory but needs to be tested more widely. Such numerically-based systems have seldom been attempted in microbiology, especially where multiple organisms have been included for the simultaneous control of several tests.