Detection of Streptococcus mutans by PCR amplification of spaP gene.

Synthetic oligonucleotide primers were used in the polymerase chain reaction (PCR) to amplify a sequence of the spaP gene, which encodes the surface protein antigen I/II of Streptococcus mutans. A DNA fragment of c. 192 bp was amplified from lysed S. mutans cells or isolated DNA. With S. mutans cells, the lower limit of detection was 4-40 cfu. With these primers, 13 reference and 50 clinical strains of S. mutans were identified. Amplification of the 192-bp product was not demonstrated when 41 strains of other streptococcal and non-streptococcal species were tested. The spaP gene PCR has potential for the rapid diagnosis of S. mutans infections.