Methods: A. actinomycetemcomitans was transformed with a Green Fluorescent Protein expression-vector and adhesion was monitored in real time in a Confocal Laser Scanning Microscope (CLSM) mounted flow cell. Average fluorescence intensity measurements of images taken over time were representative for the number of adhered A. actinomycetemcomitans. Following validation, this CLSM based parallel plate flow cell system was used for bacterial exclusion experiments. The influence of a 2 days old streptococcal biofilm coating on a glass slide on the subsequent adhesion of A. actinomycetemcomitans was evaluated.
Results: A new and reliable in vitro model for monitoring bacterial adhesion in real time under flow conditions was developed. All streptococcal strains used in this study (S. sanguinis KTH-4, S. cristatus CC5A, S. salivarius TOVE and S. mitis BMS) interfered with the adhesion of A. actinomycetemcomitans in vitro on a hard surface. The most prominent inhibition of adhesion was caused by S. sanguinis.
Conclusions: Microbial interactions during adhesion can be monitored in real time under flow conditions. The developed technique shows that so-called beneficial bacteria can counteract the adhesion of A. actinomycetemcomitans in vitro. This concept is a promising issue for the development of a new periodontal treatment approach.
This research was funded by: OT 03/52, FWO Flanders G.0240.04 and a PhD grant of the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT).