In the 60 UC patients in the discovery group, the trends in expression of IFI44L and PI3 were opposite in bacterial and viral infection, and expression differed between the two types of infection more than expression of ITGB2 (IFI44L, P < 0.001; PI3, P = 0.002; ITGB2, P = 0.015; IFI44L AUC 0.805, 95% CI 0.689-0.921; PI3 0.734, 0.604-0.865; ITGB2 0.704, 0.567-0.841; Figure 3). Here, PI3 is linked to viral infectious disease.