Comparison of culture method and real-time PCR for detection of putative periodontopathogenic bacteria in deep periodontal pockets

The goal of this study was to compare the diagnostic potential of microbiological culture and real-time polymerase chain reaction (PCR) identification, regarding patients with severe chronic periodontitis. Sixty patients were enrolled in this study and 300 microbiological samples were obtained from pockets with probing depth >7 mm. The presence of nine periodontal pathogens was evaluated with both culture analysis and real-time PCR identification. The comparison of both methods revealed a better diagnostic capability of the real-time PCR for all of the investigated pathogens, with statistically significant higher detection levels of 100% for Treponema denticola, Tanerella forsythia, Peptostreptococcus micros and Capnocytophaga gingivalis, 93.33% for Porphyromonas gingivalis, 80% for Prevotella intermedia, 76.67% for Fusobacterium nucleatum and Eubacterium nodatum, and 30% for Aggregatibacter actinomycetemcomitans. Only three pathogens were detected by using culture analysis - P. gingivalis and P. intermedia in 33.33% of the patients, and T. forsythia in 43.33% of the patients. The real-time PCR quantitative determination presented 65.82% prevalence of the red complex. Better sensitivity of the real-time PCR, when compared to the microbiological culture method, was demonstrated, in regards to the detection of the periodontal pathogens. These discrepancies may be explained by the lower detection levels of the cultivation methods, when compared to the real-time PCR and the problems of keeping pathogenic bacteria viable, which is required for the standard cultivation.