Journal of Dental Research, Vol 65, 906-908, Copyright © 1986 by International & American Associations for Dental Research Online Journals
Comparative recovery of Streptococcus mutans on five isolation media, including a new simple selective medium
M. J. Schaeken, J. S. van der Hoeven and H. C. Franken
For the isolation of Streptococcus mutans, several selective media have
been developed, of which Mitis-Salivarius Sucrose Bacitracin agar (MSB) is
the most widely used (Gold et al., 1973). Recently, the Trypticase
Yeast-Extract Cystine agar medium (TYC, de Stoppelaar et al., 1967) was
modified into a selective medium for S. mutans, called Trypticase
Yeast-Extract Cystine Sucrose Bacitracin (TYCSB, van Palenstein Helderman
et al., 1983). The aim of this study was to compare the recovery of S.
mutans from clinical samples on Mitis-Salivarius agar (MS), MSB, TYC, and
TYCSB. Further, a new simple selective medium for S. mutans was introduced.
This medium, called TSY20B, was supposed to have the same qualities as
TYCSB, but its preparation is less laborious. One hundred eighty-five
plaque and saliva samples from 37 subjects were plated on MS, MSB, TYC, and
TYCSB, and 285 samples from 23 subjects were plated on TYCSB and TSY20B.
All plates were incubated at 37 degrees C in a 91% N2, 5% CO2, 4% H2
atmosphere for five days. The S. mutans counts on TYC and TYCSB were
significantly higher than on MS or MSB by almost a factor of 10.
Seventy-seven percent of the samples gave higher S. mutans counts on TYCSB
than on MSB. Especially, samples with high S. mutans d/g numbers gave lower
S. mutans counts on MSB. These data clearly indicate that MSB agar is
inhibitory for S. mutans and should not be used. An additional advantage of
TYCSB over MSB agar is the possibility of distinguishing S. mutans
serotypes d/g from other serotypes.(ABSTRACT TRUNCATED AT 250 WORDS)
