Diversity of Veillonella spp. from subgingival plaque by polyphasic approach.

In a biofilm such as the subgingival microflora, strain-specific properties or factors induced by the host may impart a survival advantage to some bacterial strains. Periodontal disease has been associated with chronic obstructive pulmonary disease (COPD) and we previously found high amounts of Veillonella in the subgingival microflora of COPD subjects. Differentiation of Veillonella is difficult. The aims of this study were to identify subgingival Veillonella isolates by phenotypic, genetic typing and molecular genetic methods, and further, to assess if Veillonella strain properties or identity correlated with periodontal disease or COPD. From 22 subjects, 26 subgingival Veillonella isolates and one pulmonary isolate were analysed. The majority of the subgingival Veillonella isolates were identified as Veillonella parvula. Genotyping showed heterogeneity within strains of the same species. A subgingival and pulmonary isolate in one COPD subject was found to be genetically identical strains of V. parvula. Scanning electron microscopy of the lung biopsy confirmed single small cocci adhering or coaggregating with larger cocci on the airway epithelium. Apart from a variation in cellular fatty acid composition of six subgingival isolates from periodontitis subjects, no correlation between the subgingival Veillonella strains or genotypes and the presence of either periodontitis or COPD was found. In conclusion, V. parvula was the predominant subgingival Veillonella species with high genetic variability within strains of the same species. Subgingival V. parvula can translocate to the lungs; however, Veillonella identity or genotype did not correlate with periodontal disease or COPD.