Background: Sepsis is a serious impaired organ function as a result of immune dysregulation for infection. Blood culture is considered the gold standard for diagnosis of blood-stream infections, but it can be delayed up to 7 days to give a negative result. This delay makes clinicians often depend on further parameters as CBC, C-reactive protein (CRP) and proacalcitonin. Neutrophil CD64 is a glyco-protein produced at low concentration on inactive neutrophilic cell surface and obviously up regulated with the beginning of sepsis.
Methods: This study is a prospective cohort study done on 55 postoperative adult patients of elective surgeries, 33 postoperative patients with sepsis and 22 postoperative patients without sepsis, the majority of patients had more than 2 evaluations. The following parameters were done for each patient as CBC, CRP, neutrophil CD64 and blood culture. Also, follow-up samples were taken from septic group and depending on outcome, reclassification was performed for them as continued sepsis group (n = 18) and improved group (n = 15).
Results: Neutrophil CD64, N/L ratio and CRP levels were significantly increased in patients with sepsis when compared with those without sepsis (P < 0.05). The cutoff values of CD64 at 43.6% and 65.2 detected sepsis at 1st and 3rd postoperative days with 90.9%, 78.8% sensitivity and 86.4%, 90% specificity. When CD64 was combined with CRP measurement, improved diagnostic performance was noticed with specificity 100%, PPV 100%, sensitivity 72.7% and NPV 50%. Combining CD64 with N/L ratio also improved the diagnostic performance with specificity 100%, sensitivity 66.7%, NPV 45% and PPV 100%. A significant difference in levels of neutrophil CD64, N/L ratio and CRP (P < 0.01) were found between continued sepsis group and clinically improved group by using delta change percentage (dc%).
Conclusion: For postoperative sepsis, neutrophil CD64 is a good promising maker in diagnosis and follow up of patients. Combination of neutrophil CD64 with CRP and N/L ratio are better for diagnosis.