Recently, Jenkins et al reported that Manuka honey reduced the expression of a-toxin in MRSA. Expression of other virulence genes, quorum sensing genes, and genes associated with cell division was also reduced. Lee et al reported that three types of honeys (Korean acacia, Korean polyfloral, and American clover honeys) at a concentration as low as 0.5% significantly inhibited pathogenic E. coli O157:HA biofilm formation in vitro. Furthermore, low concentrations of the Korean acacia honey reduced the expression of curli genes (csgBAC ), quorum sensing genes (AI-2 importer, indole biosynthesis), and virulence genes (LEE genes) in the bacterial strain. Kronda et al reported that sublethal concentrations of Manuka honey reduced siderophore production, a virulence factor that scavenges iron for bacterial growth, in clinical and nonclinical strains of P. aeruginosa. Manuka honey has also been shown to alter the structure of P. aeruginosa; scanning and transmission electron microscopy revealed changes in cell shape and cell lysis following incubation with honey. A honey flavonoid extract was also found to alter membrane integrity and branching processes associated with virulence in C.albicans.