The challenge of growing oral spirochaetes.

Research in periodontal disease has shown the presence of oral spirochaetes repeatedly in subgingival plaque. There is uncertainty as to whether these spirochaetes are involved in the actual disease process; however, it has been shown that their presence is a definite marker for disease occurrence. An understanding of their role in periodontal disease requires further characterisation of these organisms. Diagnostic tests would be useful for the clinician and enable treatment for the patient to be planned. Studies on characterising the different treponemal species have been limited by difficulties in culturing these organisms. Moreover, there is a need to obtain pure cultures of these organisms and to identify them in order to associate particular species with disease and, ultimately, to make probes for their easy detection directly from dental plaque. This review examines the methods used, and reports our own experience, in obtaining pure cultures of oral spirochaetes. The techniques available and the problems that occur when identifying these organisms are also considered.