Targeting outer membrane protein A (OmpA) - inhibitory effect of 2'-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation.

Biofilm production facilitates microbial colonization of wounds and catheters. Acinetobacter baumannii produces high levels of biofilm and causes difficult-to-treat nosocomial infections. Candida albicans is another strong biofilm producer which may facilitate A. baumannii adhesion by providing hyphae-mediated OmpA-binding sites. Here we tested the potential of 2'-hydroxychalcones to inhibit dual-species biofilm production of A. baumannii and Candida spp., and further predicted the mechanism of structure-related difference in activity. The results suggest that 2'-hydroxychalcones exhibit potent activity against Candida spp./ A. baumannii dual-species biofilm production. Particularly active was trifluoromethyl-substituted derivative (p-CF 3 ), which decreased C. albicans / A. baumannii biomass produced on vein-indwelling parts of the central venous catheterization set by up to 99%. Further, higher OmpA-binding affinity was also calculated for p-CF 3 , which together with demonstrated significant ompA -downregulating activity, suggests that superior antibiofilm activity of this chalcone against the tested dual-species community of A. baumannii is mediated through the OmpA.