Capnocytophaga SPP. and Diabetes Mellitus-Periodontitis

Abstract

Diabetes Mellitus (OM) renders the individual more susceptible to infection and chronic periodontitis (Periodontitis) seems to be no exception. Indeed, OM-Periodontitis subjects manifest increased prevalence and severity of periodontitis than their non OM- Periodontitis counterparts. The oral bacterial flora associated with OM-Periodontitis has not been thoroughly investigated. It is hypothesised that potentially elevated glucose levels in gingival crevicular fluid in OM-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 OM-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 OM-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 OM-Periodontitis (median HbA1c = 9.3%) & 25 non-OM-Periodontitis (median HbA1c = 5.3%) subjects. Subgingival plaque samples were collected from 3 healthy (PPO .::: 3 mm) and 3 diseased sites (PPO ~ 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 < 0.001) and facultative and obligate anaerobes (P < 0.001) in diseased sites in OM-Periodontitis subjects when compared to healthy sites in non OM- Periodontitis and OM-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, OM-Periodontitis and non-OM-Periodontitis subjects. The results showed that GCF-glucose concentration was higher in diseased & healthy sites in the OM Periodontitis group. In conclusion, the results of this investigation have shown that Capnocytophaga spp. are recovered in higher numbers in OM-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.