Our previous data revealed no difference in neutrophil apoptosis after CDI between QQ and RR mice, however CXC chemokine receptor 2 (CXCR2), a neutrophil chemotactic receptor that is involved in release of mature neutrophils from bone marrow and their accumulation to sites of infection, was up-regulated in RR mice. This evidence concerns the gene CXCR2 and clostridium difficile infection.