The optimal CRP cut-off value for screening a deep infection focus was 108 mg/L at day 1 with sensitivity of 77% and specificity of 60%, 44 mg/L at day 7 with sensitivity of 68% and specificity of 67%, and 22 mg/L at day 14 with sensitivity of 59% and specificity of 76%. The gene discussed is CRP; the disease is infection.