Isopropoxy benzene guanidine: A promising new weapon against enterococcal infections

The emergence of antibiotic resistance represents a significant threat to human health. Human activities have accelerated the development of antibiotic resistance, underscoring the urgent need to develop novel antibiotics in addressing the challenge of antibiotic-resistant bacteria. Isopropoxy benzene guanidine (IBG) is a substituted benzyl guanidine derivative with good antibacterial activity against enterococci. In this study, the antibacterial activity of IBG against enterococci derived from dogs, cats, and pigs was evaluated (with a minimal inhibitory concentration range of 1–16 μg mL^–1) and the epidemiological cut-off values (ECOFFs) were determined using ECOFFinder. The ECOFFs for Enterococcus faecalis and Enterococcus faecium were both 16 μg mL^–1. The drug resistance development results showed that IBG has a low bacterial resistance risk. The antibacterial mechanism studies showed that IBG disrupts bacterial cell membranes by interacting with phosphatidylglycerol or cardiolipin. IBG inhibits the formation of E. faecalis biofilms, but it cannot eradicate them. The results of the Galleria mellonella larvae infection model and mouse dermal infection model suggested that IBG has therapeutic effects on enterococcal infections in vivo. In conclusion, IBG appears to be a good candidate for the treatment of enterococcal infections.