OBJECTIVES Antibacterial quaternary ammonium monomers (QAMs) are used in resins. The rnc gene in Streptococcus mutans (S. mutans) plays a key role in resisting antibiotics. The objectives of this study were to investigate for the first time: (1) the effects of rnc deletion on S. mutans biofilms and acid production; (2) the combined effects of rnc deletion with dimethylaminohexadecyl methacrylate (DMAHDM) on biofilm-inhibition efficacy. METHODS Parent S. mutans strain UA159 (ATCC 700610) and the rnc-deleted S. mutans were used. Bacterial growth, minimum inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) were measured to analyze the bacterial susceptibility of the parent and rnc-deleted S. mutans against DMAHDM, with the gold-standard chlorhexidine (CHX) as control. Biofilm biomass, polysaccharide and lactic acid production were measured. RESULTS The drug-susceptibility of the rnc-deleted S. mutans to DMAHDM or CHX was 2-fold higher than parent S. mutans. The drug-susceptibility did not increase after 10 passages (p < 0.05). Deleting the rnc gene increased the biofilm susceptibility to DMAHDM or CHX by 2-fold. The rnc-deletion in S. mutans reduced biofilm biomass, polysaccharide and lactic acid production, even at no drugs. DMAHDM was nearly 40 % more potent than the gold-standard CHX. The combination of rnc deletion+DMAHDM treatment achieved the greatest reduction in biofilm biomass, polysaccharide synthesis, and lactic acid production. SIGNIFICANCE Gene modification by deleting the rnc in S. mutans reduced the biofilm growth and acid production, and the rnc deletion+DMAHDM method showed the greatest biofilm-inhibition efficacy, for the first time. The dual strategy of antibacterial monomer+bacterial gene modification shows great potential to control biofilms and inhibit caries.

中文翻译：

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变形链球菌基因修饰和抗菌单体甲基丙烯酸二甲氨基十六烷基酯对生物膜生长和产酸的影响。

目的抗菌季铵单体（QAM）用于树脂中。变形链球菌（变形链球菌）中的rnc基因在抵抗抗生素中起关键作用。这项研究的目的是第一次调查：（1）rnc缺失对变形链球菌生物膜和产酸的影响；（2）rnc缺失与甲基丙烯酸二甲氨基十六烷基酯（DMAHDM）的联合作用对生物膜抑制功效的影响。方法使用变形链球菌亲本菌株UA159（ATCC 700610）和缺失rnc的变形链球菌。测量了细菌的生长，最低抑菌浓度（MIC）和最低杀菌浓度（MBC），以金标准洗必泰（CHX）为对照，分析了亲本和rnc缺失的变形链球菌对DMAHDM的细菌敏感性。生物膜生物量，测定了多糖和乳酸的产生。结果rnc缺失的变形链球菌对DMAHDM或CHX的药物敏感性比亲代变形链球菌高2倍。经过10代后，药物敏感性没有增加（p <0.05）。删除rnc基因会使生物膜对DMAHDM或CHX的敏感性增加2倍。即使在没有药物的情况下，变形链球菌的rnc缺失也减少了生物膜的生物量，多糖和乳酸的产生。DMAHDM的效力比黄金标准CHX强近40％。rnc缺失+ DMAHDM处理的组合最大程度地减少了生物膜生物量，多糖合成和乳酸的产生。意义通过删除变形链球菌中的rnc进行基因修饰，可减少生物膜的生长和产酸，rnc缺失+ DMAHDM方法首次显示出最大的生物膜抑制功效。抗菌单体+细菌基因修饰的双重策略显示出控制生物膜和抑制龋齿的巨大潜力。