Inhibition of<i> Pseudomonas aeruginosa</i> Biofilm Formation by Traditional Chinese Medicinal Herb<i> Herba patriniae</i>

Abstract

New antimicrobial agents are urgently needed to treat infections caused by drug-resistant pathogens and by pathogens capable of persisting in biofilms. The aim of this study was to identify traditional Chinese herbs that could inhibit biofilm formation of <i>Pseudomonas aeruginosa</i>, an important human pathogen that causes serious and difficult-to-treat infections in humans. A <i>luxCDABE</i>-based reporter system was constructed to monitor the expression of six key biofilm-associated genes in <i>P. aeruginosa</i>. The reporters were used to screen a library of 36 herb extracts for inhibitory properties against these genes. The results obtained indicated that the extract of <i>Herba patriniae</i> displayed significant inhibitory effect on almost all of these biofilm-associated genes. Quantitative analysis showed that <i>H. patriniae</i> extract was able to significantly reduce the biofilm formation and dramatically altered the structure of the mature biofilms of <i>P. aeruginosa</i>. Further studies showed <i>H. patriniae</i> extract decreased exopolysaccharide production by <i>P. aeruginosa</i> and promoted its swarming motility, two features disparately associated with biofilm formation. These results provided a potential mechanism for the use of <i>H. patriniae</i> to treat bacterial infections by traditional Chinese medicines and revealed a promising candidate for exploration of new drugs against <i>P. aeruginosa</i> biofilm-associated infections.