Integration of non-oral bacteria into in vitro oral biofilms

Abstract

Abbreviations: CFUs, colony forming units; CLSM, confocal laser scanning microscopy; FISH, fluorescence in situ hybridizationBiofilms are polymicrobial communities that grow on surfaces in nature. Oral bacteria can spontaneously form biofilms on the surface of teeth, which may compromise the health of the teeth, or their surrounding (periodontal) tissues. While the oral bacteria exhibit high tropism for their specialized ecological niche, it is not clear if bacteria that are not part of the normal oral microbiota can efficiently colonize and grow within oral biofilms. By using an in vitro "supragingival" biofilm model of 6 oral species, this study aimed to investigate if 3 individual bacterial species that are not part of the normal oral microbiota (Eschericia coli, Staphylococcus aureus, Enterococcus faecails) and one not previously tested oral species (Aggregatibacter actinomycetemcomitans) can be incorporated into this established supragingival biofilm model. Staphylococcus aureus and A. actinomycetemcomitans were able to grow efficiently in the biofilm, without disrupting the growth of the remaining species. They localized in sparse small aggregates within the biofilm mass. Enterococcus faecalis and E. coli were both able to populate the biofilm at high numbers, and suppressed the growth of A. oris and S. mutants. Enterococcus faecalis was arranged in a chain-like conformation, whereas E. coli was densely and evenly spread throughout the biofilm mass. In conclusion, it is possible for selected species that are not part of the normal oral microbiota to be introduced into an oral biofilm, under the given experimental microenvironmental conditions. Moreover, the equilibrated incorporation of A. actinomycetemcomitans and S. aureus in this oral biofilm model could be a useful tool in the study of aggressive periodontitis and peri-implantitis, in which these organisms are involved, respectively.

Streptococcus oralis maintains homeostasis in oral biofilms by antagonizing the cariogenic pathogen Streptococcus mutans

“…Among all tested species, omission of F. nucleatum from the biofilm composition resulted in a decrease of the total bacterial numbers. This may not be surprising as F. nucleatum is a “bridging” microorganism between early and late colonizing species, and has a scattered distribution throughout the biofilm, as shown in the present and earlier studies . Hence, absence of F. nucleatum may compromise the structural integrity of the biofilm and hinder overall microbial growth, as evidenced by the reduced total bacterial numbers in the present study.…”

“…Deciphering the interactions between species within biofilms is crucial for understanding the factors that ensure their stability, or those that drive changes that lead to dysbiosis. The Zürich in vitro biofilm models are useful tools to define such interactions of groups of species, individual species, or their virulence factors …”

“…This standardized and highly reproducible model is useful in testing the antimicrobial capacity of mouthrinses, interactions with host tissues/cells, and interactions between species and within species. For instance, in recent studies we demonstrated the effects of adding exogenous species in the supragingival biofilm, showing that Enterococcus faecalis and Staphylococcus aureus can survive and grow like endogenous species, whereas Escherichia coli can predominate in the biofilm under the experimental conditions . We have also studied the microbial dynamics that take place during the conversion from supragingival to subgingival conditions .…”

Antibiofilm activity of sandblasted and laser-modified titanium against microorganisms isolated from peri-implantitis lesions

“…12,13 Clinical strains of S. aureus, P. aeruginosa and P. gingivalis were used in this study. All species have been identified as bacteria associated with peri-implantitis in literature [27][28][29] and they were chosen among the micro-organisms isolated in the laboratory from peri-implantitis lesions which were able to produce biofilm in vitro. and chemical stability.…”

Oral infections: clinical and biological perspectives

“…[34][35][36] Thurnheer and Belibasakis have utilized an in vitro biofilm model of 6 oral species, in order to test if bacteria that are not part of the normal oral microbiota (Eschericia coli, Staphylococcus aureus, Enterococcus faecails) can efficiently colonize and grow within this oral biofilm. 37 Indeed these species were able to grow efficiently and in various structural conformations within this oral biofilm model. A derivative of this biofilm can also be used in more complex tissuebiofilm interaction models, in order to study the host response mechanisms of relevance to periodontal disease.…”