Antibacterial effectiveness of acetic acid disinfection in toothbrushes inoculated with Streptococcus mutans: an in vitro study

The aim of this study was to determine the antibacterial effectiveness of acetic acid, as disinfectant or cleaning agent for toothbrushes contaminated with Streptococcus mutans bacteria, in Franja Laboratory, a controlled environment. The study hypothesis stated that, the higher the concentration of acetic acid as a chemical agent in the disinfection of toothbrushes inoculated with Streptococcus mutans, the greater the antibacterial effectiveness. The sample used consisted of 120 toothbrushes, divided into 60 culture mediums (before and after treatment), classified into 4 groups of 15 brushes each. All 60 samples planted in the Petri dishes were submerged (before treatment); afterwards each of the samples were introduced into acetic acid in specific concentrations (5%, 10% and 15%) and were seeded again into Petri dishes (after treatment), then incubated at ± 37o C, anaerobically for 48 hours. As a result, 15% acetic acid agents showed the highest level of disinfection in toothbrushes (98.90%) within a 20 minutes time frame. Followed by 10% acetic acid with 95.0% effectiveness, followed by the 5% concentration acetic acid as the lowest degree of disinfection. Water was used as a control group and presented a very low effectiveness of disinfection leaving 80% of contamination. In conclusion, Streptococcus mutans was found to be sensitive in vitro to chemicals such as acetic acid in concentrations such as 5, 10 and 15%; showing greater sensitivity to the agent in 15% concentration.

本研究旨在受控环境弗兰哈实验室（Franja Laboratory）中，评估乙酸作为消毒剂或清洁剂，对被变形链球菌（Streptococcus mutans）污染的牙刷的抗菌效果。本研究的核心假设为：在接种变形链球菌的牙刷消毒流程中，乙酸作为化学消毒药剂的浓度越高，其抗菌效能越强。本次实验的样本共计120支牙刷，被划分为60份培养基样本（涵盖处理前与处理后两个阶段），并进一步分为4个实验组，每组各包含15支牙刷。所有接种于培养皿（Petri dishes）的60份处理前样本均被完全浸没；随后将每份样本置于特定浓度（5%、10%与15%）的乙酸溶液中进行处理，之后再次接种至培养皿（即处理后样本），并在±37℃的厌氧环境下培养48小时。实验结果显示，15%浓度的乙酸试剂在20分钟的处理周期内，对牙刷的消毒效果最佳，灭菌率达98.90%；其次为10%浓度的乙酸，灭菌率为95.0%；5%浓度的乙酸消毒效果最差。以无菌水作为对照组，其消毒效能极低，仍残留80%的细菌污染。综上，体外实验证实变形链球菌对5%、10%及15%浓度的乙酸等化学试剂具有敏感性，且对15%浓度的乙酸试剂敏感性最高。