A novel method for the identification of saliva by detecting oral streptococci using PCR

Abstract

We have used DNA amplification methods to detect common oral bacterial strains to test for the presence of saliva in forensic samples. Streptococcus salivarius and Streptococcus mutans were detected in various forms of saliva samples, whereas these streptococci were not detected in semen, urine, vaginal fluid, or on skin surfaces. Therefore, we demonstrated that these streptococci are promising new marker for the forensic identification of saliva. Our data indicated that S. salivarius is more reliable than S. mutans as an indicator of saliva presence, because the detection rates for S. salivarius and S. mutans by this method were 100% and 90%, respectively. Furthermore, S. salivarius was detected in all saliva stain samples, whereas S. mutans was only identified in 60% of the stains. Finally, using this method we were able to successfully detect S. salivarius and S. mutans in mock forensic samples. We therefore suggested that this method is useful for the identification of saliva in forensic science.