Occurrence of red-complex and aggregatibacter actinomycetemcomitans in subgingival plaque among patients with periodontal disease at the university of Nairobi dental hospital
Background: Periodontal diseases are common worldwide with chronic periodontitis affecting 80% of Kenyans. These diseases carry high morbidity if left untreated. Many microorganisms are involved in periodontal disease causation and progression including a combination of bacteria, which include gram negative bacteria such as the „red complex‟ (Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia) and Aggregatibacter actinomycetemcomitans. Studies that have described microorganisms in patients with periodontitis in Kenya are based on conventional culturing techniques. PCR was used in this study to better characterise microbial profiles of periodontal disease in patients with periodontal disease at the University of Nairobi Dental Hospital. Aim: To determine the occurrence of red complex and Aggregatibacter actinomycetemcomitans and determine the relationship between the detection frequency of these organisms in subgingival plaque with the severity of periodontal disease among patients with periodontitis attending the University of Nairobi Dental Hospital. Materials and methods: A descriptive cross-sectional study was carried out between the months of July 2013 and March 2014 at the University of Nairobi Dental Hospital. Using convenience sampling, a total of 92 persons were recruited into the study. After collection of participants‟ biodata, periodontal examination including plaque score and gingival index measurement as well as full mouth periodontal probing was done on patients with periodontal diseases and conditions and subgingival plaque collected. DNA extraction from collected plaque was done in the laboratory and presence of target bacteria including Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis was assessed in the laboratory using PCR by utilising xiv species-specific primers. Data collected was coded, entered and analysed using SPSS version 20, Microsoft Excel, and R software. Descriptive statistics were done using means and standard deviations. Chi square, Analysis of Variance, t- tests and correlation statistics were also done. Results: Using the AAP/CDC classification, majority of participants were found to have moderate or severe periodontitis. Aggregatibacter actinomycetemcomitans was found in 15.20% of participants whereas Porphyromonas gingivalis was present in 17.40% of study participants. Associations were found between presence of periodontal pathogens and age, DNA concentration in samples, the gingival index, and increasing periodontal disease severity. Discussion: There was positive association found between detection frequency of P. gingivalis and detection frequency of A. a in this study. This compared with findings of other similar microbiologic cross sectional studies that utilised molecular techniques. Positive association was also found between gender and the level of education and between frequency of tooth brushing and time of last dental visit. There was also positive association found between severity of periodontal disease and both age and time of last dental visit. Conclusion: Majority of participants in this study were found to have either moderate or severe periodontitis as defined by the AAP and CDC. Statistically significant differences were found between the severity of periodontitis in those participants who were found to have Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and those in whom the bacteria were absent. Association was therefore drawn between occurrence of the bacteria and periodontitis.