Those findings indicate that crevicular and buccal cells present internalized bacteria, regardless of periodontal status. However, higher bacterial loads are detected in cells from subjects with periodontitis.

Bacterial invasion of host epithelial cells plays an important role in the pathogenesis of periodontal diseases; however, the interactions between subgingival species and the gingival crevice cells are not fully understood. This study determined the prevalence of a group of oral bacterial species on or in epithelial cells derived from periodontal pockets and the gingival crevice of subjects with periodontitis. Samples of epithelial cells were obtained from 120 sites with periodontal pockets ¢4 mm and 92 periodontally healthy sites from 49 patients (mean age 46?3±1?4 years; 43 % males) with chronic periodontitis. Bacteria in or on epithelial cells were separated from unattached bacteria by Percoll density-gradient centrifugation. The presence and levels of 33 oral species were determined in epithelial cell samples by whole genomic DNA probes and the checkerboard method. The most frequently detected species were Porphyromonas gingivalis (42 %), Treponema denticola (38 %), Prevotella intermedia (37 %), Streptococcus intermedius (36 %), Campylobacter rectus (35 %), Streptococcus sanguinis (35 %) and Streptococcus oralis (34 %). Species of Actinomyces were found in low prevalence and levels. The data indicated that there were more micro-organisms on or in epithelial cells obtained from periodontal pockets than from healthy sulci; however, no significant differences regarding the percentage and level of any specific species were found between these sites. Veillonella parvula, S. oralis, Streptococcus gordonii and Streptococcus mitis tended to be more prevalent in sites without disease. These findings demonstrated that a wide range of oral species may be detected on or in crevicular epithelial cells from sites with periodontitis and from periodontally healthy sulci.

However, non-oral pathogens internalized in oral epithelial cells and their relationship with periodontal status are poorly understood. The purpose of this study was to detect opportunistic species within buccal and gingival crevice epithelial cells collected from subjects with periodontitis or individuals with good periodontal health, and to associate their prevalence with periodontal clinical status. Quantitative detection of total bacteria and Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis in oral epithelial cells was determined by quantitative real-time PCR using universal and species-specific primer sets. Intracellular bacteria were visualized by confocal microscopy and fluorescence in situ hybridization. Overall, 33 % of cell samples from patients with periodontitis contained at least one opportunistic species, compared with 15 % of samples from healthy individuals. E. faecalis was the most prevalent species found in oral epithelial cells (detected in 20.6 % of patients with periodontitis, P50.03 versus healthy individuals) and was detected only in cells from patients with periodontitis. Quantitative real-time PCR showed that high levels of P. aeruginosa and S. aureus were present in both the periodontitis and healthy groups. However, the proportion of these species was significantly higher in epithelial cells of subjects with periodontitis compared with healthy individuals (P50.016 for P. aeruginosa and P50.047 for S. aureus). Although E. faecalis and P. aeruginosa were detected in 57 % and 50 % of patients, respectively, with probing depth and clinical attachment level ¢6 mm, no correlation was found with age, sex, bleeding on probing or the presence of supragingival biofilm. The prevalence of these pathogens in epithelial cells is correlated with the state of periodontal disease. INTRODUCTIONThe oral cavity harbours a complex microbiota that is commonly related to oral health. Nonetheless, it is common knowledge that only some microbial consortia are associated with carious lesions and periodontal disease (Aas et al., 2005;Socransky & Haffajee, 2005). On the other hand, classically pathogenic micro-organisms can find favourable environmental conditions within and occupy specific niches of the oral cavity (Fourrier et al., 1998). Bacterial species commonly associated with nosocomial infections and multiresistance to antimicrobials, such as Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumannii, Enterococcus faecalis and the Enterobacteriaceae family, have been detected in high proportions and levels in the subgingival biofilm of individuals with periodontitis (Slots et al., 1990;Colombo et al., 2002) and in the endodontic canal (Brito et al., 2007). Furthermore, there seems to be a strong association between the presence of these pathogens in dental plaque and respiratory infections in hospitalized patients (El-Solh et al., 2004;Didilescu et al., 2005;Bahrani-Mougeot et al., 2007).Abbreviations: BOP, bleeding on probing; CAL, clinical attachment level; FISH, fluo...

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.