Peroxidase reaction as a parameter for discrimination of Streptococcus mutans and Streptococcus sobrinus

425 strains of mutans streptococci and 12 reference strains were investigat ed by membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) after aerobic and anaerobic incubation. 423 strains were identified as Streptoco ccus mutans. The remaining 2 strains were identified as Streptococcus sobri nus, The PR of 29 strains was doubtful; immediately after anaerobic incubat ion a negative PR changed into a slightly positive PR. To test the diagnost ic value of PR the strains were additionally investigated by means of speci es-specific polymerase chain reactions (PCR), The species-specific PCRs wer e developed on the basis of the respective genes of 16S rRNA of the pathoge ns S. mutans and S, sobrinus, Specificity and sensitivity were tested on re ference strains (n = 17) and negative control strains (n = 39), The results of this investigation showed that an anaerobic incubation regime could lea d to false-positive (S. mutans) or false-negative (S, sobrinus) PR. The 425 MS strains were classified as either S. mutans (n = 420) or S, sobrinus(n = 5), The findings on the reference strains required a reclassification of S, mutans V 100 into S, sobrinus V 100. Summarising, it is possible now to differentiate strains of mutans streptococci by MFAS and PR after aerobic i ncubation. Copyright (C) 2001 S. Karger AG, Basel.