Showing papers by "John Greenman published in 1996"

The Tongue Microbiota of Low Odour and Malodorous Individuals

Abstract: The tongue bacterial microbiota of 50 individuals was identified and enumerated to group or genus level. Possible relationships between these data and the oral malodour status of each individual were explored. When subjects were grouped into low or high odour producers, significant increases in the total bacterial load and key bacterial groups, namely gram-negative anaerobes, which include Porphyromonas/Prevotella species and fusiforms, were related to high odour. However, on an individual basis the extensive variation between subjects reduced the correlation between bacterial groups and odour. Two phenotypic characteristics of the microbiota, volatile sulphur production and proteolytic activity, were also assessed. These were strongly associated with odour; in particular, the proportions of hydrogen sulphide producing organisms were significantly related to the odour levels of the individuals, despite the interpersonal variation. Thus it appears that it is the metabolic activity of the mixed microbiota rather than the bacterial load, or genus types present, that most contributes to oral malodour. Keywords: oral malodour, tongue microbiota, oral bacteria, sulphide production, proteolytic activity.

Hydrolysis of Triclosan Monophosphate by Dental Plaque and Selected Species of Oral Micro-organisms

Abstract: Triclosan monophosphate is a phosphorylated derivative of the antimicrobial agent, triclosan. In comparison with triclosan, it is highly soluble in aqueous solutions. It is hypothesized that, within the oral environment, triclosan monophosphate (which may be devoid of antimicrobial activity) will be hydrolyzed into triclosan by the action of microbial phosphatases. The liberated triclosan may then exert antimicrobial activity. To test this hypothesis, we designed experiments to measure the phosphatase activity of plaque and selected species of oral micro-organisms and to demonstrate hydrolysis of triclosan monophosphate. Tests comparing the minimal inhibitory concentration and minimal bactericidal concentration of triclosan and triclosan monophosphate were also undertaken. Dental plaque and the majority of the bacterial strains tested showed phosphatase activity against p-nitrophenyl phosphate which peaked below neutral pH (acid phosphatases) or above neutral pH (alkaline phosphatases). Dental plaque showed the highest levels of alkaline phosphatase (optimum at pH 9.0) and relatively high levels of acid phosphatase (optimum at pH 6.0 to 6.5). Dental plaque and selected species of micro-organisms were all capable of hydrolyzing triclosan monophosphate, albeit at different rates. The minimal inhibitory concentration and minimal bactericidal concentration values for triclosan monophosphate against eight bacterial strains were always considerably higher than the corresponding values for triclosan. Addition of triclosan monophosphate to an established culture (ca. 10(9) cfu/mL) of Capnocytophaga gingivalis growing continuously showed that triclosan monophosphate was rapidly hydrolyzed into triclosan with concomitant loss of total bacterial viability. It is therefore likely that triclosan monophosphate will be broken down into triclosan within the oral environment with concomitant antimicrobial activity.