Synergistic Roles of Fimbriae and Gingipain Genotypes in Porphyromonas gingivalis and Their Association With Periodontitis Severity

Objective Porphyromonas gingivalis is a major periodontal pathogen periodontitis, with virulence mediated by fimbriae and gingipains. Differences in virulence may influence disease severity. This study aimed to assess the association and co‐occurrence of fimbriae and gingipain genotypes and their relationship with clinical severity in periodontitis. Materials and Methods This secondary analysis included 120 subgingival plaque samples from patients with periodontitis. Fimbriae ( fimA types I–V) and gingipain ( kgp , rgpA ) genotypes were identified using PCR and restriction enzyme digestion, and P. gingivalis load was quantified by real‐time PCR. Associations between genotypes and clinical parameters (probing depth and clinical attachment loss) were evaluated using Spearman’s correlation and chi‐square tests. Binary logistic regression assessed the association between periodontal disease severity and the presence of a combined virulence genotype, reported as odds ratios (ORs). Results The fimA types II and III and gingipain genotypes kgp-I and kgp-II were significantly associated with deeper PD and greater CAL ( p < 0.05). fimA type II was the most prevalent across all bacterial load percentiles, followed by type IV. kgp-I and rgpA type A were correlated with higher P. gingivalis counts. Significant positive correlations were observed between fimbriae and gingipain genotypes ( p < 0.05). Patients with CAL ≥5 mm had significantly higher odds of harboring the combined virulence genotype than those with CAL