The composition of oral lactoflora in chronic periodontitis and healthy subjects differs, with a higher prevalence of homofermentative lactobacilli, particularly L. gasseri, in the latter group. Both homo- and heterofermentative oral lactobacilli suppress the growth of periodontal pathogens, but the antimicrobial properties are strain, species and origin specific.

Aims:  The monoclonal antibody 61BG1·3, recognizing the RgpA protease, has been reported to confer protection against recolonization by the periodontal pathogen Porphyromonas gingivalis in humans. The aim of this study was to express a functional scFv derived from the monoclonal antibody 61BG1·3 on the surface of Lactobacillus paracasei for potential use in the prevention or treatment of periodontal diseases. Methods and Results:  The scFv was fused to an E‐tag and cloned in the Escherischia coli/Lactobacillus shuttle vector pLP501, which mediates surface expression of the scFv. FACS analysis using an anti‐E‐tag antibody revealed that the scFv was expressed on the surface of the transformed lactobacilli and binding of the scFv to RgpA was shown by ELISA. Lact. paracasei expressing the scFv against RgpA was able to agglutinate P. gingivalis whereas the Lact. paracasei expressing an irrelevant scFv fragment did not. Scanning electron microscopy demonstrated efficient binding of the lactobacilli expressing the scFv anti‐RgpA to P. gingivalis. Conclusions:  We have expressed a functional scFv antibody directed against the RgpA protease of P. gingivalis in Lactobacillus. Significance and Impact of the Study:  These results suggest a potential of Lactobacillus expressing scFvs against P. gingivalis to be used to combat periodontal disease.

Our aim was to find out differences between chronic periodontitis (CP) and periodontally healthy subjects with respect to oral lactic acid bacteria (LAB) as well as subgingival microbial relations. Clinical data, salivary levels of lactobacilli and mutans streptococci, and subgingival microbial samples were obtained from 26 CP and 15 periodontally healthy subjects. Antimicrobial activity of LAB against periodontal pathogens was assessed. We found Actinobacillus actinomycetemcomitans , Porphyromonas gingivalis and Prevotella intermedia /nigrescens in 54%, 23% and 73% of CP patients, respectively; the latter was also found in 47% of healthy subjects. The mean proportion of streptococci (27.0 vs 15.2%), particularly S. mutans group (5.7 vs 0.8%) and S. mitis group (18.1 vs 5.0%), as well as aerobic coryneforms (24.7 vs 11.9%) was higher in healthy persons (pB/ 0.05). An inverse relationship of subgingival streptococci and aerobic coryneforms with periodontal pathogens and deteriorated clinical parameters were seen. Salivary counts of mutans streptococci were higher in healthy persons. Inhibition of periodontal pathogens by LAB was observed. In conclusion, the proportions of oral LAB were significantly lower in CP than in healthy subjects, whilst being important antagonists against periodontal pathogens. These oral commensals may play an important role in the suppression of periodontal pathogens and maintenance of microecological balance in the oral cavity.

Our aim was to find out differences between chronic periodontitis (CP) and periodontally healthy subjects with respect to oral lactic acid bacteria (LAB) as well as subgingival microbial relations. Clinical data, salivary levels of lactobacilli and mutans streptococci, and subgingival microbial samples were obtained from 26 CP and 15 periodontally healthy subjects. Antimicrobial activity of LAB against periodontal pathogens was assessed. We found Actinobacillus actinomycetemcomitans , Porphyromonas gingivalis and Prevotella intermedia /nigrescens in 54%, 23% and 73% of CP patients, respectively; the latter was also found in 47% of healthy subjects. The mean proportion of streptococci (27.0 vs 15.2%), particularly S. mutans group (5.7 vs 0.8%) and S. mitis group (18.1 vs 5.0%), as well as aerobic coryneforms (24.7 vs 11.9%) was higher in healthy persons (pB/ 0.05). An inverse relationship of subgingival streptococci and aerobic coryneforms with periodontal pathogens and deteriorated clinical parameters were seen. Salivary counts of mutans streptococci were higher in healthy persons. Inhibition of periodontal pathogens by LAB was observed. In conclusion, the proportions of oral LAB were significantly lower in CP than in healthy subjects, whilst being important antagonists against periodontal pathogens. These oral commensals may play an important role in the suppression of periodontal pathogens and maintenance of microecological balance in the oral cavity.

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