| Abstract [eng] |
Title. Saliva Microbiota Composition and the Prevalence of Antimicrobial Resistance Genes in Patients with Periodontal Diseases and Salivary Flow Disorders. Relevance of the problem and aim of the work. Saliva, rich in microorganisms, links all areas of the mouth. It is known that periodontitis is not caused by individual microorganisms, rather by their dysbiosis. However, the saliva microbiota of Lithuanians with periodontal diseases has not been analysed yet. Various saliva microorganisms might exhibit antimicrobial resistance genes and complicate the treatment of oral and systemic diseases. Therefore, this thesis aims to analyse the saliva microbiota composition of individuals with periodontal diseases and salivary flow disorders and to establish the prevalence of antimicrobial resistance genes. Material and methods. During clinical examinations, unstimulated whole saliva sialometry and a questionnaire survey were conducted. Metagenome sequencing using the 16S rRNA gene was employed to identify saliva bacteria. The data on microbiota composition was compared between groups, formed according to the modified Community Periodontal Index. The polymerase chain reaction and electrophoresis methods were applied to analyse the antimicrobial resistance genes. IBM SPSS 29.0 software was used for the statistical analysis. Results. Study revealed that the saliva of all 55 tested contained at least one antimicrobial resistance gene. The most prevalent (n=54, 98,2%) were the blaTEM and tetM genes. Metagenome analysis of the saliva of 34 individuals showed that 13 (38,2%) suffered with gingivitis (CPIm 1), 12 (35,3%) had periodontal pockets of 4-5 mm (CPIm 3), 9 (26,5%) exhibited the periodontal pockets of 6 mm and deeper (CPIm 4). Group comparison at the genera level revealed dominant bacteria: Prevotella in CPIm 4, Streptococcus in CPIm 3, both Leptotrichia and Neisseria in CPIm 1. The saliva of individuals in CPIm 3 and CPIm 4 groups had higher relative quantities of Treponema and Porphyromonas compared to those with gingivitis. Lastly, CPIm 4 showed relatively higher presence of Filifactor, Selenomonas, and Fusobacterium, while CPIm 3 – Haemophilus. Conclusions. The taxonomic relative abundance of saliva microbiota in individuals with different periodontal conditions did not differ significantly; however, in the groups with the periodontal pockets deeper than 4 mm, substantial abundance of periodontal pathogens was found. Antimicrobial resistance genes, potentially causing resistance to medication and treatment failure, were identified. However, further research is needed so that a complete and comprehensive understanding on the qualities of saliva microbiota and the prevalence of resistant genes would be formed. |
