In vitro Antibacterial Activity of an FDA-Approved H+-ATPase Inhibitor, Bedaquiline, Against Streptococcus mutans in Acidic Milieus

Virtual Screening of Inhibitors of Streptococcus mutans Biofilm from Lonicera japonica flos and Activity Validation

In this study, potential inhibitors of Streptococcus mutans biofilm were screened from Lonicera japonica flos using semiflexible molecular docking. A total of 88 metabolites from L. japonica flos and 14 biofilm-related proteins of S. mutans were analyzed, and 25 compounds were initially screened out. Subsequently, 9 compounds with higher availability were subjected to experimental validation, confirming that 6 of them effectively inhibit the S. mutans biofilm formation. Notably, chlorogenic acid was found to potentially disrupt the GbpC protein, which plays a role in the sucrose-dependent adhesion pathway. Similarly, oleanolic acid appeared to impede the adhesin P1 protein involved in the sucrose-independent adhesion mechanism, corroborating the computational predictions. The results of this study provide essential insights for leveraging L. japonica flos in the creation of dental-care-related products and food items aimed at oral health.

The microbiome and the gut-lung axis in tuberculosis: interplay in the course of disease and treatment

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis (MTB) that remains a significant global health challenge. The extensive use of antibiotics in tuberculosis treatment, disrupts the delicate balance of the microbiota in various organs, including the gastrointestinal and respiratory systems. This gut-lung axis involves dynamic interactions among immune cells, microbiota, and signaling molecules from both organs. The alterations of the microbiome resulting from anti-TB treatment can significantly influence the course of tuberculosis, impacting aspects such as complete healing, reinfection, and relapse. This review aims to provide a comprehensive understanding of the gut-lung axis in the context of tuberculosis, with a specific focus on the impact of anti-TB treatment on the microbiome.

Characterization of Mycobacterium abscessus colony-biofilms based on bi-dimensional images

Mycobacterium abscessus biofilm aggregates have been shown in the lungs of cystic fibrosis patients and are often tolerant to drugs. Herein, we analyzed bi-dimensional images of either fluorescent or Congo red-stained M. abscessus colony-biofilms grown on a membrane to monitor growth and shape of M. abscessus smooth and rough variants. These colony-biofilms responded differently to rifabutin and bedaquiline, thus highlighting the importance of the morphotype to properly address antibiotic treatment in patients with biofilm-related infections.

Small Molecule Compounds, A Novel Strategy against Streptococcus mutans

Dental caries, as a common oral infectious disease, is a worldwide public health issue. Oral biofilms are the main cause of dental caries. Streptococcus mutans (S. mutans) is well recognized as the major causative factor of dental caries within oral biofilms. In addition to mechanical removal such as tooth brushing and flossing, the topical application of antimicrobial agents is necessarily adjuvant to the control of caries particularly for high-risk populations. The mainstay antimicrobial agents for caries such as chlorhexidine have limitations including taste confusions, mucosal soreness, tooth discoloration, and disruption of an oral microbial equilibrium. Antimicrobial small molecules are promising in the control of S. mutans due to good antimicrobial activity, good selectivity, and low toxicity. In this paper, we discussed the application of antimicrobial small molecules to the control of S. mutans, with a particular focus on the identification and development of active compounds and their modes of action against the growth and virulence of S. mutans.

A New pH-Responsive Nano Micelle for Enhancing the Effect of a Hydrophobic Bactericidal Agent on Mature Streptococcus mutans Biofilm

The bactericidal effect on biofilm is the main challenge currently faced by antibacterial agents. Nanoscale drug-delivery materials can enhance biofilm penetrability and drug bioavailability, and have significant applications in the biomedical field. Dental caries is a typical biofilm-related disease, and the acidification of biofilm pH is closely related to the development of dental caries. In this study, a pH-responsive core-shell nano micelle (mPEG-b-PDPA) capable of loading hydrophobic antibacterial agents was synthesized and characterized, including its ability to deliver antibacterial agents within an acidic biofilm. The molecular structure of this diblock copolymer was determined by hydrogen-1 nuclear magnetic resonance (¹H-NMR) and gel permeation chromatography (GPC). The characters of the micelles were studied by dynamic light scattering (DLS), TEM, pH titration, and drug release detection. It was found that the hydrophilic micelles could deliver bedaquiline, a hydrophobic antibacterial agent on S. mutans, in acidic environments and in mature biofilm. No cytotoxic effect on the periodontal cells was detected within 48 h. This pH-responsive micelle, being able to load hydrophobic antibacterial agent, has good clinical application potential in preventing dental caries.