In vitro antimicrobial activity of a novel compound, Mul-1867, against clinically important bacteria

Background: The antimicrobial activity of Mul-1867, a novel synthetic compound, was tested against 18 bacterial strains, including clinical isolates and reference strains from culture collections. Methods: The minimal inhibitory concentration (MICs) and minimal bactericidal concentration (MBCs) were determined by using the broth macrodilution method. The kinetics of the inhibitory effects of Mul-1867 against biofilm-growing microorganisms was assessed at time-kill test in vitro against 48-h-old biofilms of Staphylococcus aureus and Escherichia coli. Transmission electron microscopy analyses was conducted to examine cell disruption. Results: A comparative assessment of the antimicrobial activities of Mul-1867 and chlorhexidine digluconate (CHG), used as a control antimicrobial, indicated that Mul-1867 was significantly more effective as a disinfectant than CHG. Mul-1867 showed potent antimicrobial activities against all the tested bacteria (MIC: 0.03-0.5 mu g/mL). Furthermore, MBC/MIC ratio of Mul-1867 for all tested strains was less than or equal to 4. Time-kill studies showed that treatment with Mul-1867 (0.05-2 %) reduced bacterial numbers by 2.8-4.8 log10 colony forming units (CFU)/mL within 15-60 s. Bactericidal activity of Mul-1867 was confirmed by morphological changes revealed by TEM suggested that the killing of bacteria was the result of membrane disruption. Conclusion: Overall, these data indicated that Mul-1867 may be a promising antimicrobial for the treatment and prevention of human infections.