Ciantar, Marilou; (2002) Capnocytophaga spp. and Diabetes Mellitus-Periodontitis. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Diabetes Mellitus (DM) renders the individual more susceptible to infection and chronic periodontitis (Periodontitis) seems to be no exception. Indeed, DM-Periodontitis subjects manifest increased prevalence and severity of periodontitis than their non- DM-Periodontitis counterparts. The oral bacterial flora associated with DM-Periodontitis has not been thoroughly investigated. It is hypothesised that potentially elevated glucose levels in gingival crevicular fluid in DM-Periodontitis subjects could confer an ecological advantage for saccharolytic organisms such as Capnocytophaga spp. Members of this genus have been recovered from a range of periodontal diseases including DM-Periodontitis. In vitro studies have shown that Capnocytophaga spp. grow better and produce more enzymes relevant to periodontal destruction when grown in glucose-enriched conditions that simulate the human diabetic situation. The main aim of this study was to investigate whether Capnocytophaga spp. were more prevalent in DM-Periodontitis. Prior to commencement of the clinical study, fastidious anaerobe agar (FAA) was identified as the best culture medium for the recovery of these species from clinical samples. Identification of Capnocytophaga clinical isolates to species level was based on 16S rRNA PCR-RFLP with Cfo I as the restriction enzyme, developed specifically as part of this study. The clinical study comprised 21 DM-Periodontitis (median HbAic = 9.3%) and 25 non-DM-Periodontitis (median HbAic = 5.3%) subjects. Subgingival plaque samples were collected from 3 healthy (PPD [less than] 3 mm) and 3 diseased sites (PPD [more than] 5 mm) per subject. Total counts for Capnocytophaga spp. and (facultative and obligate) anaerobes from each sample were determined. A total of 848 Capnocytophaga clinical isolates were isolated and identified using 16S rRNA PCR-RFLP. Statistical analyses were performed using multilevel modelling. The results showed significantly higher numbers of Capnocytophaga spp. (P [less than] 0.001) and facultative and obligate anaerobes (P [less than] 0.001) in diseased sites in DM-Periodontitis subjects when compared to healthy sites in non- DM-Periodontitis and DM-Periodontitis subjects. A proportion (39%) of Capnocytophaga clinical isolates were subjected to antimicrobial sensitivity testing. The majority were sensitive to most of the antibacterial agents used in clinical practice, with the exception of metronidazole. A micro-assay for the quantification of GCF- glucose was developed and used to quantify the GCF-glucose concentration in healthy, DM-Periodontitis and non-DM-Periodontitis subjects. The results showed that GCF-glucose concentration was higher in diseased and healthy sites in the DM- Periodontitis group. In conclusion, the results of this investigation have shown that Capnocytophaga spp. are recovered in higher numbers in DM-Periodontitis patients, and more so in the diseased sites in these patients. This could be due to the different subgingival ecological environment resulting from the elevated levels of GCF-glucose at these sites.

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