| dc.description.abstract | Introduction Primary Immunodeficiencies, or primary immunodeficiency disorders (PID), are a rare inherited group of heterogenous disorders which can variably affect the immune system. To date, there are around 485 PID’s, now termed inborn errors of immunity, including 55 novel monogenic gene defects and the overall incidence of PID is 1:10,000. Periodontitis in children and adolescents have a relatively low prevalence, ranging from 0.1-1% however, in children with PID, periodontitis is a common finding. Children affected often present with pain, bleeding difficulty eating, bad breath and premature tooth loss. Aim The investigation and description of the oral microbiota present in subgingival plaque of children with PID in comparison to clinically healthy children, at baseline and post non-surgical periodontal therapy Methods 48 patients recruited for participation in this study (test n=24, control n=24). The clinical component was completed and published prior to this thesis. Microbiology analysis of plaque samples was completed using 16S sequencing techniques of V1-V2 and V3-V4 hypervariable regions. V1-V2 region were used for the analysis. Statistical testing of differences between sample groups were conducted using permutational multivariate analysis of variance (PERMANOVA) as implemented in the Paleontological Statistics (PAST) software (v4.10) for 64-bit Windows. Alpha diversity of the samples and multivariate ordination using beta diversity distances and metrics such as Bray-Curtis, Jaccard, Morisita, Horn, Kulczynski was also analysed using the PAST software. Results Periodontitis was diagnosed in 7 test participants (29%), gingivitis in 8 (30%) and gingival health in 9 (37%). Control participants reported 4 patients with gingivitis (6%) and gingival health in 20 participants (83%). No control participants were diagnosed with periodontits. The V1-V2 ASVs uniquely mapped to 361 human microbial taxa in total, at over 98% identity. The following phyla were identified; Absconditabacteria (SR1), Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Gracilibacteria (GN02), Proteobacteria, Saccharibacteria (TM7), Spirochaetes, Synergistetes. The most abundant phyla for the controls and test follow-up was Proteobacteria closely followed by Firmicutes. Baseline test participants, included Firmicutes followed by Actinobacteria and Proteobacteria. Alpha diversity indicated that baseline had a high diversity, richness and evenness, which reduced after patients receiving treatment. Beta diversity analysis yielded significance with Bray- Curtis (p=0.001) for test participants at baseline vs follow-up, and further significance with Horn and Morista metrics (p=0.0037 and p=0.046 respectively) for test vs. controls. ‘SIMPER’ test found the most common species noted for comparisons across all groups were Streptococcus sp. [HMT064], Lautropia mirabilis, Streptococcus oralis. Saccharibacteria (TM7) [G-1] bacterium HMT 346, Leptotrichia hofstadii and Cardiobacterium hominis were also identified in higher proportions within test groups. Known periodontal pathogens, A. actinomycetemcomitans, Prevotella intermedia, P. gingivalis, Treponema denticola, Tannerella forsythia, were found in a small number of the test participants, but only in 5 participants and at very low abundances (<1%). Conclusion The findings within the statistical and descriptive analysis have shown that children affected by neutrophil defects do present with different microbiological profile in comparison to healthy controls, and that the microbiome is altered following treatment of gingivitis or periodontitis. | en_US |
