Biofilm-forming Ability of Anaerobic Bacterial Strains Isolated from Patients Diagnosed with Periodontitis

Bacterial biofilms represent the primary causative agents of pathogenic processes within the oral cavity. Biofilm microorganisms exhibit heightened resistance to adverse environmental factors. The objective of this study was to ascertain the biofilm-forming potential of clinical strains of anaerobic microorganisms isolated from the periodontal pocket of patients diagnosed with periodontitis. The study of biofilm formation was carried out by the method (Djordjevic et al., 2002) using flat-bottomed 96-well polystyrene microtitration plates. Biofilm formation was determined by staining with 0.1% crystal violet. The study utilised clinical strains isolated from the periodontal pocket of 61 patients diagnosed with grade III chronic periodontitis. Of these, 30 strains belonging to three bacterial species were selected for further analysis: Porphyromonas asaccharolytica, Slackia exigua, and Schaalia odontolytica. Among the Porphyromonas asaccharolytica strains, 80% formed biofilm; the figure for Slackia exigua was 90%, and for Schaalia odontolytica - 80%. In total, 25 strains were capable of biofilm formation. The results indicate that the isolated strains of Porphyromonas asaccharolytica, Slackia exigua, and Schaalia odontolytica exhibited a significant capacity for biofilm formation (83.3% of the strains formed biofilm), particularly Slackia exigua strains, which exhibited the highest number of strains with high biofilm formation ability - 5 (16.6%). It is also noteworthy that these microorganisms exhibited a moderate persistence frequency (16.4% each), of the total sample of microbial biocenoses from inflammatory periodontal soft tissue areas.