TLR4 and colitis: In order to address the impact of TLR4 in MDR PA colonization and subsequent intestinal as well as extra-intestinal immune responses in murine IL10−/− colitis, we perorally challenged 11–14 months old conventionally colonized TLR4 deficient IL10−/− mice and IL10−/− counterparts with 109 CFU of a clinical MDR PA isolate by gavage.