Determination of biofilm formation and associated gene detection in Staphylococcus genus isolated from the oral cavity under inflammatory periodontal diseases

Abstract

Background. Inflammatory periodontal diseases, including chronic periodontitis, are accompanied by a chronic persisting inflammatory process. The latter process and biofilm-forming potential are the factors that contribute to the formation of antibiotic-resistant microorganism strains. The purpose of our work was to study the biofilm-forming ability of antibiotic-resistant biofilm-forming Staphylococcus genus bacteria isolated from the oral cavities of patients suffering from periodontitis, and check the presence of the genes associated with biofilm formation in these bacteria. Material and methods. Isolates were obtained from patients suffering from chro­nic periodontitis using differentially diagnostic nutrient media. Chemotaxonomic identification of the antibiotic-resistant isolates was performed on the Microflex LT device. Biofilm-forming potential was studied in plastic Petri dishes by spectrophotometric method. The antibiotic sensitivity of the bacteria and microscopic fungi was identified by the disc diffusion method. The presence of icaA, icaD, icaC, icaB, agrA, srtA genes was detected in two multiplex polymerase chain reactions (mPCR). 16S rRNA gene and icaR genes were amplified in a separate PCR. Results. Opportunistic microbial associations dominate in the microbiom of the oral cavity under conditions of periodontitis; besides, in the majority of cases, Staphyloco­ccus genus bacteria were present in associations. In 73 % (131/180) of cases, bacte­ria from Staphylococcus genus represented by six species – S. aureus, S. haemolyticus, S. saprophyticus, S. epidermidis, S. xelosus, and S. hominis were isolated from the nidus during the inflammatory process. From the oral cavities of the patients with inflamma­tory periodontitis, 51 biofilm-forming strains of S. aureus, 29 strains of S. haemolyticus, 12 strains of S. saprophyticus, and 12 strains of S. epidermidis were isolated. It was established that antibiotic-resistant isolates of S. aureus possess the genetic determinants which are now believed to be connected with icaA, icaC, icaB icaA, icaR, agrA, and srtA biofilm-forming potential. Two non-biofilm forming strains of S. aureus were proven to lack the genes responsible for the biofilm-forming ability. Conclusion: It has been established that microbial associations with a prevailing share of Staphylococcus genus bacteria, most of which have a biofilm-forming potential, dominate in the microbiom of the oral cavity under conditions of periodontitis.

Keywords

• antibiotic resistance
• microbial associations
• staphylococcus genus bacteria
• biofilm formation