Oral lactoflora in chronic periodontitis and periodontal health

Our aim was to characterize oral lactobacilli for their antimicrobial properties, survival in various environmental conditions and antibiotic susceptibility reflecting their potential use as probiotics.Material and methods.Sixty-seven salivary and subgingival lactobacilli of periodontally healthy humans were identified using rapid amplified ribosomal DNA restriction analysis and partial sequencing of the 16S-rDNA fragment.Their antimicrobial activity against five oral pathogens, acid and bile tolerance and susceptibility to 13 antibiotics were tested.Results.Ten species were identified.The majority of strains suppressed growth of Streptococcus mutans, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia, but none inhibited Candida albicans.The strongest antimicrobial activity was associated with facultatively heterofermentative lactobacilli and homofermentative L. salivarius.Sixty-five of 67 strains survived for 4 h at pH 3.0 but only 28 were able to grow at this pH.Survival following 4 h of incubation at pH 2.5 was observed for 25 of 31 strains but none of the strains grew at this pH.Half of the strains were able to grow at bile concentration of 5% (v/v).Conclusions.Strains of L. plantarum, L. paracasei, L. salivarius and L. rhamnosus showed both good antimicrobial activity and good tolerance of environmental conditions that make them suitable for using as probiotic candidates.At the same time, the strains of L. plantarum differ from the natural resistance pattern of lactobacilli and therefore, the absence of transferable resistance genes in these strains should be confirmed.