Detection and comparison of prevalence of Porphyromonas gingivalis through culture and Real Time-polymerase chain reaction in subgingival plaque samples of chronic periodontitis and healthy individuals

INTRODUCTION: The micro-flora of oral cavity is a myriad of micro-organism. Any infection of oral cavity leads to diseased condition which is a transitional transformation of the micro-organism in a specific paradigm depending upon the diseased condition. Periodontitis is one of the predominant chronic diseases which is a multifactorial infection. Porphyromonas gingivalis is a key etiological agent in causing periodontitis. To study the predominance of these bacteria in the diseased condition is important to detect, quantify and to find its efficacy by comparing different methods for identification. AIM AND OBJECTIVES: The aim of the study is to determine the prevalence of P. gingivalis by anerobic culture and by real-time polymerase chain reaction (PCR) from subgingival plaque samples of chronic periodontitis and healthy individual and to compare efficacy of two methods. MATERIALS AND METHODS: A total of 400 subjects were considered, and subgingival plaque was collected using paper points. Individual were equally divided into two groups: chronic periodontitis (200) and healthy individuals (200). Each plaque sample collected was divided into two aliquots of which the first aliquot was subjected for anerobic culture to isolate P. gingivalis. Phenotypical identification was done morphologically and biochemically further quantification of P. gingivalis was done by colony-forming unit. The second aliquot was subjected for DNA extraction and real-time PCR was conducted to detect and quantify P. gingivalis using specific primer. RESULTS: Out of 400 samples, 73% showed detection of P. gingivalis by culture method and through reverse transcription-PCR (RT-PCR), the detection was 75%. Individual detection of P. gingivalis by culture in chronic periodontitis was 89.5% and 54.4% in healthy individuals, while detection by RT-PCR was found to be 91.5% in chronic periodontitis and 58% in healthy individuals. However, comparison between two techniques in detection of P. gingivalis was statistically insignificant. CONCLUSION: When we compared RT-PCR with culture RT-PCR showed higher positivity. RT-PCR is more sensitive and requires less time to detect. However, in the present study, culture also showed good positivity, suggesting proper dilution and with extended incubation, the specificity of culture can be improved to a great extent.