Quantitative detection of P.gingivalis and fimAII/IV in smoker-chronic periodontitis patients

FimA genotypes of Porphyromonas gingivalis differ in prevalence among periodontitis patients and in phenotypic traits, suggesting differences in their virulence potential. Objective: to determine if levels of P.gingivalis genotypes fimA II and IV correlate with pocket depth in smoker-chronic periodontitis patients. Methods: Chronic non-treated periodontitis patients (n=20), smokers were selected. Subgingival samples were obtained from 9 sites per patient [3 shallow (<3mm), 3 intermediate (4-6mm) and 3 deep (>7mm)], and analyzed by Real-time PCR using primers specific for P.gingivalis 16SrRNA, fimA II and fimA IV. Results: P.gingivalis and genotype fimA IV were detected in at least one site in all subjects, whereas genotype fimA II was detected in 18 subjects (90%). P.gingivalis was detected in 152 of 168 sites (90.5%) and genotypes II and IV were detected in 47 (28%) and 117 (69.6%) sites, respectively. The proportion of genotypes II and IV in relation to P.gingivalis levels was similar in shallow, intermediate and deep pockets (15.5%, 17.7% and 11.7% for genotype IV and 2.4%, 4.6% and 1.4% for genotype II, respectively), indicating that other genotypes may be more abundant than the two studied genotypes. Levels of P.gingivalis and of genotype II did not differ among different pocket depths. However, increased levels of genotype IV were significantly associated with increasing pocket depth (25.6±43.1 for shallow; 70.2±38.2 for intermediate and 142±54.6 for deep pockets)(log 10/µl of sample) (Friedman, p<0.05). The data indicated that in smoker-chronic periodontitis Brazilian patients, genotype IV is not only more prevalent and abundant in periodontal pockets than genotype II, but its levels are associated with probing pocket depth. Conclusions: The data suggested an association between P.gingivalis genotype fimA IV and disease severity in smoker-chronic periodontitis subjects.