Real-time polymerase chain reaction for detection and quantification of bacteria in periodontal patients

BACKGROUND: Accurate laboratory tests for the detection and quantification of periodontopathogens in subgingival plaque samples of periodontal disease patients are becoming essential to study the pathogenesis of this polymicrobial condition. We used a real-time polymerase chain reaction (PCR) assay for the quantification of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Dialister pneumosintes, Campylobacter rectus, and Micromonas micros as well as total eubacteria in subgingival plaque samples from individuals with periodontitis. METHODS: Eighty-three subgingival samples from periodontally diseased patients and 43 samples from periodontally healthy subjects were tested and the results of bacterial quantification were correlated to clinical parameters. Quantification was performed with specific 16S rRNA target sequences with double fluorescence labeled probes and serial dilutions of plasmid standards by real-time PCR. RESULTS: Results showed that patients as well as healthy subjects were positive for the presence of target periodontopathogens; however, median values were higher in samples from periodontitis subjects. In addition, a positive association was observed between colonization at high levels by P. gingivalis and M. micros and the presence of deep periodontal pockets. CONCLUSION: Real-time PCR provides a reliable high-throughput method for quantification of periodontopathogens and may be useful for understanding the complex etiology observed in periodontal diseases.