Efficiency of various growth media in recovering oral bacterial flora from human dental plaque.

Abstract

MM10 sucrose blood agar (MM10 SB agar), N(2)C agar, Schaedler agar (SH agar), and mitis salivarius agar (MS agar) were tested for their ability to recover human dental plaque flora by a continuous anaerobic procedure and by a conventional anaerobic method. MM10 SB agar yielded higher recovery of bacteria from plaque samples as determined by the enumeration of colony-forming units (CFU). The CFU on N(2)C agar, SH agar, and MS agar were lower than MM10 SB agar when the continuous anaerobic procedure was used. The superior performance of MM10 SB agar was much more apparent when used for the cultivation of dental plaque by the conventional anaerobic method. Under these conditions the counts were consistently higher on MM10 SB agar as compared to the other media tested. However, the differential counts of Streptococcus sanguis and S. mutans from carious plaque samples were in general comparable on all culture media. Deletion of blood from MM10 SB agar did not lower counts. The elimination of dithiothreitol from this medium resulted in a significantly lower recovery of bacteria from the plaque samples when cultured by the conventional anaerobic method. The storage of MM10 SB agar for varying periods of time aerobic conditions did not seem to affect its performance. These findings suggest that MM10 SB agar is an ideal culture medium for the isolation, nonselective enumeration, and differential counts of bacteria present in normal and disease-associated plaques.