By dividing the serum CRP value by the amount of CD11b on neutrophils, we derived a novel marker of Gram-positive sepsis, CRP/CD11b ratio, which displayed 76% sensitivity and 80% specificity for the detection of Gram-positive sepsis (n = 17) among febrile patients with microbiologically confirmed or clinically diagnosed bacterial infection. The gene discussed is ITGAM; the disease is bacterial infectious disease.