Enhanced antibacterial effect against Enterococcus faecalis by silver ions plus Triton X-100 with low concentrations and cytotoxicity

Screening structure and predicting toxicity of pesticide adjuvants using molecular dynamics simulation and machine learning for minimizing environmental impacts

Surfactants as synergistic agents are necessary to improve the stability and utilization of pesticides, while their use is often accompanied by unexpected release into the environment. However, there are no efficient strategies available for screening low-toxicity surfactants, and traditional toxicity studies rely on extensive experimentation which are not predictive. Herein, a commonly used agricultural adjuvant Triton X (TX) series was selected to study the function of amphipathic structure to their toxicity in zebrafish. Molecular dynamics (MD) simulations, transcriptomics, metabolomics and machine learning (ML) were used to study the toxic effects and predict the toxicity of various TX. The results showed that TX with a relatively short hydrophilic chain was highly toxic to zebrafish with LC50 of 1.526 mg/L. However, TX with a longer hydrophilic chain was more likely to damage the heart, liver and gonads of zebrafish through the arachidonic acid metabolic network, suggesting that the effect of surfactants on membrane permeability is the key to determine toxic results. Moreover, biomarkers were screened through machine learning, and other hydrophilic chain lengths were predicted to affect zebrafish heart health potentially. Our study provides an advanced adjuvants screening method to improve the bioavailability of pesticides while reducing environmental impacts.

Triton X-100 enhanced antibacterial effect of photodynamic therapy against Enterococcus faecalis infection: an in vitro study

Photodynamic therapy (PDT) is an effective method for bacterial infection control in root canals of teeth with a broad-spectrum antibacterial activity. However, its application in root canal treatment is limited due to its inefficiency under hypoxic conditions and dentin staining. Triton X-100 (TX) shows great potential in enhancing the efficiency of antimicrobial agents through improving bacterial membrane permeability. The present study employed a combination of toluidine blue O (TB)-mediated PDT with TX to target the Enterococcus faecalis (E. faecalis), a bacterium with strong resistance to various antibacterial agents and mostly detected in infected root canals. PDT combined with TX showed enhanced antibacterial efficiency against both planktonic cells and biofilms of E. faecalis. At the same time, TX enhanced the antibacterial effect in dentinal tubules and reduced the incubation time. Mechanism studies revealed that TX improved reactive oxygen species (ROS) production through increasing the proportion of TB monomers. Additionally, increased membrane permeability and wettability were also observed. The findings demonstrated the PDT combined with TX could be used as a highly effective method for the root canal disinfection of teeth.

Triton X-100 counteracts antibiotic resistance of Enterococcus faecalis: An in vitro study

OBJECTIVES

The high prevalence of antibiotic-resistant bacteria poses a threat to the global public health. The appropriate use of adjuvants to restore the antimicrobial activity of antibiotics against resistant bacteria could be an effective strategy for combating antibiotic resistance. In this study, we investigated the counteraction of Triton X-100 (TX-100) and the mechanisms underlying the antibiotic resistance of Enterococcus faecalis (E. faecalis).

METHODS

Standard, wild-type (WT), and induced antibiotic-resistant E. faecalis strains were used in this study. In vitro antibacterial experiments were conducted to evaluate the antimicrobial activities of gentamicin sulfate and ciprofloxacin hydrochloride in the presence and absence of 0.02 % TX-100 against both planktonic and biofilm bacteria. Transcriptomic and untargeted metabolomic analyses were performed to explore the molecular mechanisms of TX-100 as an antibiotic adjuvant. Additionally, membrane permeability, membrane potential, glycolysis-related enzyme activity, intracellular adenosine triphosphate (ATP), and expression levels of virulence genes were assessed. The biocompatibility of different drug combinations was also evaluated.

RESULTS

A substantially low TX-100 concentration improved the antimicrobial effects of gentamicin sulfate or ciprofloxacin hydrochloride against antibiotic-resistant E. faecalis. Mechanistic studies demonstrated that TX-100 increased cell membrane permeability and dissipated membrane potential. Moreover, antibiotic resistance and pathogenicity of E. faecalis were attenuated by TX-100 via downregulation of the ABC transporter, phosphotransferase system (PTS), and ATP supply.

CONCLUSIONS

TX-100 enhanced the antimicrobial activity of gentamicin sulfate and ciprofloxacin hydrochloride at a low concentration by improving antibiotic susceptibility and attenuating antibiotic resistance and pathogenicity of E. faecalis.

CLINICAL SIGNIFICANCE

These findings provide a theoretical basis for developing new root canal disinfectants that can reduce antibiotic resistance.

Mechanisms of Triton X-100 reducing the Ag+-resistance of Enterococcus faecalis

To investigate the mechanism of Triton X-100 (TX-100) reducing the Ag+-resistance of Enterococcus faecalis (E. faecalis), and evaluate the antibacterial effect of TX-100 + Ag+ against the induced Ag+-resistant E. faecalis (AREf). The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of AgNO3 against E. faecalis with/without TX-100 were determined to verify the enhanced antibacterial activity. Transmission electron microscopy (TEM) was used to observe the morphological changes of E. faecalis after treatment. The intra- and extracellular concentration of Ag+ in treated E. faecalis was evaluated using inductively coupled plasma mass spectrometer (ICP-MS). The changes in cell membrane potential and integrity of treated E. faecalis were also observed using the flow cytometer. Moreover, AREf was induced through continuous exposure to sub-MIC of Ag+ and the antibacterial effect of TX-100 + Ag+ on AREf was further evaluated. The addition of 0.04% TX-100 showed maximal enhanced antibacterial effect of Ag+ against E. faecalis. The TEM and ICP-MS results demonstrated that TX-100 could facilitate Ag+ to enter E. faecalis through changing the membrane structure and integrity. Flow cytometry further showed the effect of TX-100 on membrane potential and permeability of E. faecalis. In addition, the enhanced antibacterial effect of TX-100 + Ag+ was also confirmed on induced AREf. TX-100 can facilitate Ag+ to enter E. faecalis through disrupting the membrane structure and changing the membrane potential and permeability, thus reducing the Ag+-resistance of E. faecalis and enhancing the antibacterial effect against either normal E. faecalis or induced AREf.

Antibiofilm and antimicrobial activity of temporary filling materials on root canals: an in situ acid challenge

The present study evaluated the antibiofilm and antimicrobial effects of temporary restorative materials on root canals after an intra-oral challenge. Seventy roots were endodontically treated and divided into 5 groups: high-viscosity glass ionomer (HV-GIC), light-activated glass ionomer (RM-GIC), zinc-oxide cement without eugenol (ZO), zinc-oxide cement with eugenol (ZOE), and unsealed roots (negative control). For 28 days, 14 participants used intra-oral devices with five roots, and drops of sucrose were applied onto them. The amount of biofilm and the bacterial counts were analyzed by Kruskal-Wallis and Dunn, and by two-way ANOVA and Tukey (α = 0.05). HV-GIC and RM-GIC better inhibit biofilm, followed by ZO and ZOE. Unsealed roots had the largest biofilm accumulation (p = 0.002) and higher bacterial penetration than restored roots (p = 0.023). A low amount of Streptococcus was found in RM-GIC and ZOE-restored roots without difference from HV-GIC (p = 0.021). The low amount of Enterococcus (p = 0.003) was found in the ZOE-restored roots, without difference from GICs.

Root-shaped antibacterial alginate sponges with enhanced hemostasis and osteogenesis for the prevention of dry socket

Tooth extraction commonly causes uncontrolled bleeding, loss of blood clots, and bacterial infection, leading to the dry socket and bone resorption. Thus, it is highly attractive to design a bio-multifunctional scaffold with outstanding antimicrobial, hemostatic, and osteogenic performances for avoiding dry sockets in clinical applications. Herein, alginate (AG)/quaternized chitosan (Qch)/diatomite (Di) sponges were fabricated via electrostatic interaction, Ca²⁺ cross-linking, as well as lyophilization methods. The composite sponges are facilely made into the shape of the tooth root, which could be well integrated into the alveolar fossa. The sponge shows a highly interconnected and hierarchical porous structure at the macro/micro/nano levels. The prepared sponges also possess enhanced hemostatic and antibacterial abilities. Moreover, in vitro cellular assessment indicates that the developed sponges have favorable cytocompatibility and significantly facilitate osteogenesis by upregulating the formation of alkaline phosphatase and calcium nodules. The designed bio-multifunctional sponges display great potential for trauma treatment after tooth extraction.