CRP/CD11b ratio: a novel parameter for detecting gram-positive sepsis

To commence proper antibiotic treatment in sepsis, timely knowledge of whether the cause of systemic infection is gram-negative (gram−) or gram-positive (gram+) bacteria in origin would be beneficial for clinicians. In this clinical prospective study, our objective was to develop a method for distinguishing between gram+ and gram− bacterial infection. In gram− bacterial infection (n = 21), the average amount of CD11b on neutrophils was significantly higher than in gram+ bacterial infection (n = 22). On the contrary, serum C-reactive protein (CRP) level was significantly higher in gram+ than in gram− bacterial infection. By dividing the serum CRP value by the amount of CD11b on neutrophils, we derived a novel marker of gram+ sepsis, CRP/CD11b ratio, which displayed 76% sensitivity and 80% specificity for the detection of gram+ sepsis (n = 17) among febrile patients with microbiologically confirmed or clinically diagnosed bacterial infection. The detection of gram+ sepsis is possible after the combination of neutrophil CD11b data and serum CRP level. In conclusion, our findings indicate that the proposed CRP/CD11b ratio test could potentially assist physicians in determining an appropriate antibiotic treatment in patients with severe bacterial infection.