Evaluation of methods of transport and cultivation of bacterial specimens from infected dental root canals.

Five different methods of transport and cultivation of bacteria from dental root canal specimens were evaluated. Bacteria were recovered from 29 percent of the specimens when they were transported in VMG IV and subcultured in PRAS medium or on the surface of blood agar in an anaerobic box. When a PRAS-peptone-yeast extract broth was used for transport and the specimens were initially subcultured in the broth, bacteria were recovered from 49 percent of the specimens. When fluid thioglycollate medium USP (BBL) and Clausen medium (Oxoid) were used for transport as well as for initial subculture, bacteria were recovered from 58 percent and 47 percent of the specimens, respectively. The high recovery of bacteria by these media could to a significant degree be ascribed to the use of the media for initial subculture of the specimens. Recovery of bacteria by fluid thioglycollate medium USP was as good or even better as with the more elaborate PRAS medium. Fluid thioglycollate medium USP in screw-capped vials requires no special equipment in the dental clinic and is recommended for use in routine dental practice.