Quaternary ammonium-induced multidrug tolerant Streptococcus mutans persisters elevate cariogenic virulence in vitro

Abstract

Dental caries are the most prevalent chronic infections in the oral cavity, and Streptococcus mutans acts as the main cariogenic bacterial species. Antibacterial quaternary ammonium compounds (QAs) have been developed to preveFnt or treat dental caries. However, there is no report on the tolerance of S. mutans to QAs. In this study, we investigated the development of S. mutans persistence induced by a novel dental caries defensive agent, dimethylaminododecyl methacrylate (DMADDM), for the first time. Typical biphasic killing kinetics for persisters were observed in both S. mutans planktonic and biofilm cultures challenged by DMADDM at concentrations of 20 and 200 μg·mL−1, respectively. The persisters tolerated six other antibiotics with different antibacterial mechanisms, while only daptomycin and vancomycin could slightly reduce the persister numbers in planktonic cultures. The distribution of persisters in DMADDM-treated biofilms was similar to that in the untreated control, except that the total biomass and biofilm height were significantly reduced. A higher exopolysaccharides (EPS):bacteria ratio was observed in DMADDM-treated biofilms. Persisters in biofilms significantly upregulated gtf gene expression, indicating an increase in the bacteria’s ability to produce EPS and an elevated capability of cariogenic virulence. Carbon source metabolism was significantly reduced, as related metabolic genes were all downregulated in persisters. Concentrations of 0.1 mM, 1 mM and 10 mM of extra glucose significantly reduced the number of persisters both in planktonic and biofilm conditions. The formation of non-inheritable and multidrug tolerant persisters induced by DMADDM suggested that drug tolerance and new persistent eradication strategies should be considered for oral antibacterial agents.

Resumptive Streptococcus mutans Persisters Induced From Dimethylaminododecyl Methacrylate Elevated the Cariogenic Virulence by Up-Regulating the Quorum-Sensing and VicRK Pathway Genes

“…The water-soluble glucans, as a rich carbon source, may play an important role depending on the state of persister biofilms. Our previous study proved that in the dormant state, the addition of glucose significantly reduced the number of persister cells (Jiang et al, 2017). It indicated that the addition of carbon sources can reverse the dormancy of the bacteria to resuscitation.…”

“…In our previous work, we have monitored the expression of several key glycolysis-and citrate cycle-related genes in S. mutans persister cells, including adhE, ldh, and pdhA/B/C/D. The expression levels of these genes were all significantly downregulated in persistent cells compared to the control group, suggesting the low metabolic level of S. mutans persisters (Jiang et al, 2017). Contrarily, in this study we observed the S. mutans persisters were metabolically active in "lag time" when they reverse from dormancy to regrowth in terms of quorum-sensing and two component system VicRK pathways.…”

“…Then different concentrations of DMADDM above the MIC were employed to induce the S. mutans persisters. The persistent cells were then evaluated in time-dependence killing curve as described in previous work (Jiang et al, 2017). In brief, aliquots of overnight culture of S. mutans were diluted in BHI broth to obtain the final concentration of 1 × 10 6 CFU/ml.…”

“…A novel quaternary ammonium monomer, dimethylaminododecyl methacrylate (DMADDM) was proved to be a potential anti-caries dental material due to its long-lasting and remarkable antibacterial effects and well biocompatibility in vitro and in vivo (Cheng et al, 2013;Mei et al, 2013;Wang et al, 2016;Zhang et al, 2016). We identified that lethal concentration of DMADDM can induce the formation of S. mutans persisters by decreasing the metabolism for the first time (Jiang et al, 2017). The induction of S. mutans persistence by DMADDM highlighted the critical evaluation of drug resistance/tolerance when developing antibacterial dental materials.…”

Threats to adhesive/dentin interfacial integrity and next generation bio‐enabled multifunctional adhesives

“…For example, the quaternary amines dimethylaminododecyl methacrylate (DMADDM) and benzalkonium chloride (BZK) induced development of drug resistance in a biofilm model of S. gordonii . Likewise, exposure to the QAC DMAHDM induced drug tolerance in an S. mutans biofilm model …”