Detection of Lactobacillus reuteri in saliva using FTA™ Elute cards and polymerase chain reaction-technique

Background: Probiotic bacteria have been used for centuries to obtain a better health and the majority of publications have focused on the gut health. More recent studies do also investigate if the bacteria could have any effect in the oral microflora. Since probiotic products are becoming more common on the market, it is interesting to investigate if these probiotic bacteria exist in the oral cavity and if they exert any therapeutic effect on oral diseases. The aim of this study was to determine an uncomplicated method capable of measuring one bacterium associated with caries prophylactic properties. Methods: Saliva from three test subjects were collected before and after chewing on a tablet containing Lactobacillus reuteri. DNA from each saliva sample was extracted using FTA™ elute cards and amplified with a PCR. Saliva samples were cultured on Rogosa agar for comparison. Saliva after chewing was diluted for determination of detection level using Rogosa agar counts as standard. Amplified samples were analysed from stained electrophoresis gels.Results: The PCR method could detect Lactobacillus reuteri in saliva if the content was 250 CFU/mL or higher. An increase in CFU/mL in saliva after chewing can be observed. Saliva could before chewing show in two out of three test subjects no amplifiable DNA whilst after chewing all did.Conclusions: A method considered uncomplicated that is capable of detecting Lactobacillus reuteri in saliva has been developed. Detection level was 250 CFU/mL