The subgingival microbiota of Brazilians with untreated chronic periodontitis were complex, including high proportions of periodontopathogens commonly found in other populations, as well as some unusual species.

The ecological diversity of the periodontal microenvironment may provide suitable conditions for the colonization of species not usually considered members of the oral microbiota. In this investigation, we aimed to determine the prevalence and levels of pathogenic species of medical relevance in the microbiota of individuals with distinct periodontal clinical status. Subgingival biofilm was obtained from patients with periodontal health (H, n = 81), gingivitis (G, n = 55), generalized aggressive (AgP, n = 36) or chronic periodontitis (CP, n = 98), and analyzed for 39 microbial taxa using a checkerboard DNA-DNA hybridization technique. Microbial differences among groups, as well as associations between clinical and microbiological parameters were sought by non-parametric and univariate correlation tests. Neisseria spp., Peptostreptococus anaerobius, Candida albicans, enterobacteria, Pseudomonas aeruginosa, Eubacterium saphenum, Clostridium difficile and Olsenella uli were detected in high mean prevalence and counts in the subgingival microbiota of the study population. Species that were more related to periodontal inflammation and tissue destruction at the patient and site levels included enterobacteria, C. albicans, Neisseria spp., P. aeruginosa, O. uli, Hafnia alvei, Serratia marcescens and Filifactor alocis (p < 0.05). In contrast, Fusobacterium necrophorum, Lactobacillus acidophilus, Staphylococcus aureus and Streptococcus pneumoniae were associated with periodontal health (p < 0.05). Pathogenic species of medical importance may be detected in high prevalence and levels in the periodontal microbiota. Regardless of their role in periodontal health or disease, the periodontal biofilm may be a source for dissemination and development of systemic infections by these pathogenic microorganisms.

Putative periodontal pathogens and non-oral bacteria alone or in association were strongly associated with periodontitis.

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The purpose of this study was to evaluate the prevalence of Actinomyces species, streptococci, and Enterococcus faecalis in primary root canal infections by using a molecular genetic method. Samples were obtained from 53 infected teeth, of which 27 cases were diagnosed as acute periradicular abscesses. DNA was extracted to evaluate the occurrence of 13 bacterial species by using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Polymerase chain reaction using an ubiquitous bacterial primer was undertaken to check the presence of bacterial DNA in clinical samples. All root canal samples contained bacteria as demonstrated by polymerase chain reaction. The checkerboard DNA-DNA hybridization assay allowed the detection of streptococci in 22.6% of the samples, Actinomyces species in 9.4%, and E. faecalis in 7.5%. The most prevalent species were members of the Streptococcus anginosus group. With regard to the asymptomatic lesions, the most prevalent species were S. intermedius (11.5% of the cases), E. faecalis (11.5%), and S. anginosus (7.7%). S. constellatus was the most prevalent species in pus samples (25.9% of the cases). The other most prevalent species in abscessed teeth were A. gerencseriae (14.8%), S. gordonii (11.1%), S. intermedius (11.1%), A. israelii (7.4%), S. anginosus (7.4%), and S. sanguis (7.4%). S. constellatus was the only species positively associated with acute periradicular abscess (p < 0.01).

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Local or systemically administered tetracycline results in transitory selection of subgingival species intrinsically resistant to this drug. Although the percentage of sites harboring periodontal pathogens resistant to tetracycline were quite elevated in this population, both therapies were effective in reducing their prevalence over time.

Putative periodontal pathogens are more prevalent in the subgingival microbiota of HIV-seronegative patients with chronic periodontitis, whereas species not usually associated with periodontitis are detected in higher frequency in HIV-seropositive subjects under HAART.