Effect of bacterial aggregation on the adherence of oral streptococci to hydroxyapatite

Abstract

Several in vitro assay systems to measure the adherence of human dental plaque bacteria to solid surfaces such as teeth, glass, and hydroxyapatite have been published. In many studies a variety of macromolecular solutes have been used to study the adherence process. Often these solutes are able to aggregate the test bacteria and thus may alter the outcome of adherence experiments. In this study, the effects of the aggregation of Streptococcus sanguis on adherence to spheroidal hydroxyapatite is described. Adherence of preformed aggregates and of bacteria which were aggregating during the adherence reaction was examined. Bacteria were aggregated with whole saliva, concanavalin A, and wheat germ lectin. Further effects of the coaggregation of S. mitis and Actinomyces viscosus to saliva-coated spheroidal hydroxyapatite are presented. These studies suggest that formation of large aggregates resulted in a decrease in the numbers of organisms which adhered. In contrast, the formation of small aggregates actually increased the numbers of bacteria that adhered. All increases in adherent bacteria occurred at low concentrations of aggregating substance in which visible bacterial aggregation was not evident. The data indicate that adequate dose-response experiments must be performed to ensure that solutes used as probes to study adherence mechanisms do not affect the adherence simply as a result of aggregation of the test microorganisms.

A synergistic chlorhexidine/chitosan combination for improved antiplaque strategies

“…Furthermore, Chit 1 seemed to have inhibitory or detaching effects on the adherence of the test strain, shown by a lower cell density after its application. These findings support the proposal that chitosan could be a promising candidate for the therapeutical interference of dental plaque formation by interactions of their positive charged free amino groups with anionic parts of the bacterial cell walls and their ability of bacterial aggregation (20,21).…”

Transmission electron microscopy of early microbial colonization of human enamel and root surfaces in vivo

“…However, it has been proposed that the aggregation factors may play a dual role during the process of colonization. Thus several studies have indicated that the formation of large bacterial aggregates may actually result in a decrease in the number of adhering microorganisms (22,23). It is therefore highly unlikely that the globular structures observed by SAXTON (20) represent bacterial aggregates.…”

Adhesion of Streptococcus rattus and Streptococcus mutans to metal surfaces

“…The formation of cell aggregates may have directly influenced the sticrose-dependent adhesion. LILJEMARK et al (11) suggested that the formation of small aggregates of S. sanguis in saliva increased the number of adhering bacteria while the formation of large cell aggregates resulted in a decrease in the number of adhering organisms, VAN HOUTE (12) suggested a similar mechanism for S. mutans by which glucan-indoced aggregation would diminish the attachment of aggregates of S. mutans to oral surfaces. ROLLA et al (13) recently suggested a model for sucrose mediated attachment of bacteria to solid surfaces such as teeth.…”