Effect of Polyhexamethylene Biguanide in Combination with Undecylenamidopropyl Betaine or PslG on Biofilm Clearance

Abstract

Hospital-acquired infection is a great challenge for clinical treatment due to pathogens' biofilm formation and their antibiotic resistance. Here, we investigate the effect of antiseptic agent polyhexamethylene biguanide (PHMB) and undecylenamidopropyl betaine (UB) against biofilms of four pathogens that are often found in hospitals, including Gram-negative bacteria <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i>, Gram-positive bacteria <i>Staphylococcus aureus</i>, and pathogenic fungus, <i>Candida albicans</i>. We show that 0.02% PHMB, which is 10-fold lower than the concentration of commercial products, has a strong inhibitory effect on the growth, initial attachment, and biofilm formation of all tested pathogens. PHMB can also disrupt the preformed biofilms of these pathogens. In contrast, 0.1% UB exhibits a mild inhibitory effect on biofilm formation of the four pathogens. This concentration inhibits the growth of <i>S</i>. <i>aureus</i> and <i>C. albicans</i> yet has no growth effect on <i>P. aeruginosa</i> or <i>E. coli</i>. UB only slightly enhances the anti-biofilm efficacy of PHMB on <i>P. aeruginosa</i> biofilms. However, pretreatment with PslG, a glycosyl hydrolase that can efficiently inhibit and disrupt <i>P. aeruginosa</i> biofilm, highly enhances the clearance effect of PHMB on <i>P. aeruginosa</i> biofilms. Meanwhile, PslG can also disassemble the preformed biofilms of the other three pathogens within 30 min to a similar extent as UB treatment for 24 h.