Relationship of the subgingival microbiota to a chairside test for aspartate aminotransferase in gingival crevicular fluid

Background: The aim of the present study was to evaluate the association be tween the occurrence of certain specific periodontal pathogens and aspartat e aminotransferase (AST) levels in gingival crevicular fluid (GCF). Methods: Thirty systemically healthy subjects with moderate to advanced per iodontitis were selected. Within each subject, the AST contents of GCF from sites with probing depth between 5 mm and 7 mm were measured using a chair side colorimetric test. AST-positive site refers to one that had an AST lev el greater than or equal to 800 mu IU. Subgingival plaque samples from one AST-positive and one negative site were collected for microbiological exami nation. One site with probing depth less than or equal to 3 mm and no gingi val inflammation was selected as a healthy control. Clinical parameters of the chosen sites, including the plaque index and gingival index scores, pro bing depth, and clinical attachment level were measured. Culture and immuno fluorescence (IF) were used for detecting common periodontal pathogens, inc luding Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, Cam pylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Capnocytop haga species, Prevotella intermedia, Prevotella melaninogenica, and Porphyr omonas gingivalis. Logistic regression was used to analyze the correlation between the AST test and certain specific pathogens. Results: The GCF scores and total cultivable bacterial counts were higher i n AST-positive sites than either AST-negative or healthy sites. The prevale nce and proportions of specific periodontal pathogens such as C. rectus, E. corrodens, F. nucleatum, Capnocytophaga species, P. intermedia, and P. gin givalis were significantly higher in positive than in negative sites. In an alyzing the correlation of the proportion of 6 pathogens with the AST test by logistic regression, only P. gingivalis showed a significant positive co rrelation. The odds ratio of having a high proportion of P. gingivalis in t he presence of a positive AST test was 1.21. Conclusions: The present study showed that at AST-positive sites, there is a higher prevalence and higher proportion of certain periodontal pathogens. Although only the correlation of P. gingivalis and AST values was statisti cally significant, the results imply that certain periodontal pathogens may be associated with elevation of AST levels in GCF.