ENUMERATION OF VIABLE ORAL SPIROCHETES FROM PERIODONTAL POCKETS

We recently developed a successful method for quantifying oral anaerob ic spirochetes in pure culture by a viable count. New oral spirochete medium was used with low temperature-gelling agarose in polystyrene ti ssue-culture flasks. We have extended the use of this method to determ ine the viable count of spirochetes from periodontal pockets. Sixteen subgingival plaque samples were obtained by insertion of sterile paper points into deep periodontal pockets. The points were placed into red uced transport medium at chairside, vortexed in the microbiology labor atory and aliquots of the medium inoculated into molten new oral spiro chete-agarose medium (37 degrees C) containing rifampin (20 mu g/ml) i n a flask. Subsequent dilutions were made from this initial flask to o ther flasks containing selective medium in sequence. All flasks were i ncubated anaerobically. Most other subgingival bacteria were selective ly inhibited by rifampin. Spirochete colonies were typically spherical and were either dense or cottony. Their identities were checked by da rkfield examination. Counts of colony-forming units of cultivable spir ochetes ranged from 12.5% to 28.2% of the total cultivable anaerobic f lora by the method described.