Effects of a sub-minimum inhibitory concentration of chlorhexidine gluconate on the development of multi-species biofilms.

Following antimicrobial administrations in oral environments, bacteria become exposed to a sub-minimum inhibitory concentration (sub-MIC), which can induce single-species biofilms. This study explored the effects of chlorhexidine gluconate (CHG) at a sub-MIC on multi-species biofilms comprising , and . CHG at a sub-MIC was found to induce biofilm growth, although the bacterial growth was not significantly different from that in the control. The gene transcription related to multi-species biofilm formation with CHG at a sub-MIC was significantly higher than that of the control, but this was not found in single-species biofilms. The bio-volume of extracellular polysaccharides with CHG at a sub-MIC was significantly higher than that of the control. This suggests that CHG at a sub-MIC may promote the development of multi-species biofilms by affecting the gene transcription related to biofilm formation.