Chlorhexidine Hydrochloride

This study aimed to develop dual-functional CMC-LYZ-ACP nanogels. Three different antibacterial substances, tea polyphenols (TPs), silver nitrate (AgNO₃), and chlorhexidine (CHX) are then combined to form three dual-functional CMC-LYZ-ACP nanogels for remineralization and antibacterial purposes.

An in vitro model of Streptococcus mutans biofilm was established to analyze the inhibitory effect of the antibacterial-remineralizing dual-functional nanogels on the biofilm. And the nanogels were applied to the surface of demineralized enamel to assess their remineralization efficacy.

The three remineralization-antibacterial dual-functional CMC-LYZ-ACP nanogels exhibited stable particle sizes within 200 nm and were all negatively charged nanospherical structures. They demonstrated significant inhibitory effects against Streptococcus mutans and achieved good remineralization outcomes both in vitro and in vivo.

The incorporation of the three antibacterial agents (AgNO₃, TPs, CHX) endowed the CMC-LYZ-ACP nanogels with excellent antibacterial properties, inhibiting the growth of plaque biofilms while maintaining their potent remineralization capabilities.

Remineralizing demineralized enamel while inhibiting biofilm adhesion and formation of caries-inducing bacteria can block caries and provide new strategies for early enamel caries treatment.

ST11 is the most common lineage among carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with significant differences in microbial characteristics among K. pneumoniae isolates. Here, we investigated the genetic determinants and critical characteristics associated with distinct morphotypes of ST11 CRKP. An ST11-KL47 CRKP isolate carrying a pLVPK-like virulence plasmid was isolated from a patient with a bloodstream infection; the isolate had the "mcsw" morphotype. Two distinct morphotypes ("ntrd" and "msdw") were derived from this strain during in vitro passage. Whole genome sequencing was used to identify mutations that cause the distinct morphotypes of ST11 CRKP. Transmission electron microscopy, antimicrobial susceptibility tests, growth assays, biofilm formation, virulence assays, membrane permeability assays, and RNA-seq analysis were used to investigate the specific characteristics associated with different morphotypes of ST11 CRKP. Compared with the parental mcsw morphotype, the ntrd morphotype resulted from mutation of genes involved in capsular polysaccharide biosynthesis (wza, wzc, and wbaP), a result validated by gene knockout experiments. This morphotype showed capsule deficiency and lower virulence potential, but higher biofilm production. By contrast, the msdw morphotype displayed competition deficiency and increased susceptibility to chlorhexidine and polymyxin B. Further analyses indicated that these characteristics were caused by interruption of the sigma factor gene rpoN by insertion mutations and deletion of the rpoN gene, which attenuated membrane integrity presumably by downregulating the phage shock protein operon. These data expand current understanding of genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 CRKP.